diff --git a/cluster/copy.go b/cluster/copy.go
new file mode 100644
index 0000000..49a5673
--- /dev/null
+++ b/cluster/copy.go
@@ -0,0 +1,115 @@
+package cluster
+
+import (
+	"github.com/hdt3213/godis/interface/redis"
+	"github.com/hdt3213/godis/lib/utils"
+	"github.com/hdt3213/godis/redis/protocol"
+	"strconv"
+	"strings"
+)
+
+const copyToAnotherDBErr = "ERR Copying to another database is not allowed in cluster mode"
+const noReplace = "NoReplace"
+const useReplace = "UseReplace"
+
+// Copy copies the value stored at the source key to the destination key.
+// the origin and the destination must within the same node.
+func Copy(cluster *Cluster, c redis.Connection, args [][]byte) redis.Reply {
+	if len(args) < 3 {
+		return protocol.MakeErrReply("ERR wrong number of arguments for 'copy' command")
+	}
+	srcKey := string(args[1])
+	destKey := string(args[2])
+	srcNode := cluster.peerPicker.PickNode(srcKey)
+	destNode := cluster.peerPicker.PickNode(destKey)
+	replaceFlag := noReplace
+	if len(args) > 3 {
+		for i := 3; i < len(args); i++ {
+			arg := strings.ToLower(string(args[i]))
+			if arg == "db" {
+				return protocol.MakeErrReply(copyToAnotherDBErr)
+			} else if arg == "replace" {
+				replaceFlag = useReplace
+			} else {
+				return protocol.MakeSyntaxErrReply()
+			}
+		}
+	}
+
+	if srcNode == destNode {
+		return cluster.relay(srcNode, c, args)
+	}
+	groupMap := map[string][]string{
+		srcNode:  {srcKey},
+		destNode: {destKey},
+	}
+
+	txID := cluster.idGenerator.NextID()
+	txIDStr := strconv.FormatInt(txID, 10)
+	// prepare Copy from
+	srcPrepareResp := cluster.relayPrepare(srcNode, c, makeArgs("Prepare", txIDStr, "CopyFrom", srcKey))
+	if protocol.IsErrorReply(srcPrepareResp) {
+		// rollback src node
+		requestRollback(cluster, c, txID, map[string][]string{srcNode: {srcKey}})
+		return srcPrepareResp
+	}
+	srcPrepareMBR, ok := srcPrepareResp.(*protocol.MultiBulkReply)
+	if !ok || len(srcPrepareMBR.Args) < 2 {
+		requestRollback(cluster, c, txID, map[string][]string{srcNode: {srcKey}})
+		return protocol.MakeErrReply("ERR invalid prepare response")
+	}
+	// prepare Copy to
+	destPrepareResp := cluster.relayPrepare(destNode, c, utils.ToCmdLine3("Prepare", []byte(txIDStr),
+		[]byte("CopyTo"), []byte(destKey), srcPrepareMBR.Args[0], srcPrepareMBR.Args[1], []byte(replaceFlag)))
+	if protocol.IsErrorReply(destPrepareResp) {
+		// rollback src node
+		requestRollback(cluster, c, txID, groupMap)
+		return destPrepareResp
+	}
+	if _, errReply := requestCommit(cluster, c, txID, groupMap); errReply != nil {
+		requestRollback(cluster, c, txID, groupMap)
+		return errReply
+	}
+	return protocol.MakeIntReply(1)
+}
+
+// prepareCopyFrom is prepare-function for CopyFrom, see prepareFuncMap
+func prepareCopyFrom(cluster *Cluster, conn redis.Connection, cmdLine CmdLine) redis.Reply {
+	if len(cmdLine) != 2 {
+		return protocol.MakeArgNumErrReply("CopyFrom")
+	}
+	key := string(cmdLine[1])
+	existResp := cluster.db.ExecWithLock(conn, utils.ToCmdLine("Exists", key))
+	if protocol.IsErrorReply(existResp) {
+		return existResp
+	}
+	existIntResp := existResp.(*protocol.IntReply)
+	if existIntResp.Code == 0 {
+		return protocol.MakeErrReply("ERR no such key")
+	}
+	return cluster.db.ExecWithLock(conn, utils.ToCmdLine2("DumpKey", key))
+}
+
+func prepareCopyTo(cluster *Cluster, conn redis.Connection, cmdLine CmdLine) redis.Reply {
+	if len(cmdLine) != 5 {
+		return protocol.MakeArgNumErrReply("CopyTo")
+	}
+	key := string(cmdLine[1])
+	replaceFlag := string(cmdLine[4])
+	existResp := cluster.db.ExecWithLock(conn, utils.ToCmdLine("Exists", key))
+	if protocol.IsErrorReply(existResp) {
+		return existResp
+	}
+	existIntResp := existResp.(*protocol.IntReply)
+	if existIntResp.Code == 1 {
+		if replaceFlag == noReplace {
+			return protocol.MakeErrReply(keyExistsErr)
+		}
+	}
+	return protocol.MakeOkReply()
+}
+
+func init() {
+	registerPrepareFunc("CopyFrom", prepareCopyFrom)
+	registerPrepareFunc("CopyTo", prepareCopyTo)
+}
diff --git a/cluster/copy_test.go b/cluster/copy_test.go
new file mode 100644
index 0000000..11771fe
--- /dev/null
+++ b/cluster/copy_test.go
@@ -0,0 +1,120 @@
+package cluster
+
+import (
+	"github.com/hdt3213/godis/lib/utils"
+	"github.com/hdt3213/godis/redis/connection"
+	"github.com/hdt3213/godis/redis/protocol/asserts"
+	"testing"
+)
+
+func TestCopy(t *testing.T) {
+	conn := new(connection.FakeConn)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("FlushALL"))
+
+	// cross node copy
+	srcKey := testNodeA.self + utils.RandString(10)
+	value := utils.RandString(10)
+	destKey := testNodeB.self + utils.RandString(10)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value))
+	result := Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", srcKey))
+	asserts.AssertBulkReply(t, result, value)
+	result = testNodeB.db.Exec(conn, utils.ToCmdLine("GET", destKey))
+	asserts.AssertBulkReply(t, result, value)
+	// key exists
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey))
+	asserts.AssertErrReply(t, result, keyExistsErr)
+	// replace
+	value = utils.RandString(10)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey, "REPLACE"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", srcKey))
+	asserts.AssertBulkReply(t, result, value)
+	result = testNodeB.db.Exec(conn, utils.ToCmdLine("GET", destKey))
+	asserts.AssertBulkReply(t, result, value)
+	// test copy expire time
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value, "EX", "1000"))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey, "REPLACE"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("TTL", srcKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+	result = testNodeB.db.Exec(conn, utils.ToCmdLine("TTL", destKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+
+	// same node copy
+	srcKey = testNodeA.self + utils.RandString(10)
+	value = utils.RandString(10)
+	destKey = srcKey + utils.RandString(2)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", srcKey))
+	asserts.AssertBulkReply(t, result, value)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", destKey))
+	asserts.AssertBulkReply(t, result, value)
+	// key exists
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey))
+	asserts.AssertIntReply(t, result, 0)
+	// replace
+	value = utils.RandString(10)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey, "REPLACE"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", srcKey))
+	asserts.AssertBulkReply(t, result, value)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("GET", destKey))
+	asserts.AssertBulkReply(t, result, value)
+	// test copy expire time
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value, "EX", "1000"))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey, "REPLACE"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("TTL", srcKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("TTL", destKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+
+	// test src prepare failed
+	*simulateATimout = true
+	srcKey = testNodeA.self + utils.RandString(10)
+	destKey = testNodeB.self + utils.RandString(10) // route to testNodeB, see mockPicker.PickNode
+	value = utils.RandString(10)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value, "ex", "1000"))
+	result = Rename(testNodeB, conn, utils.ToCmdLine("RENAME", srcKey, destKey))
+	asserts.AssertErrReply(t, result, "ERR timeout")
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("EXISTS", srcKey))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("TTL", srcKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+	result = testNodeB.db.Exec(conn, utils.ToCmdLine("EXISTS", destKey))
+	asserts.AssertIntReply(t, result, 0)
+	*simulateATimout = false
+
+	// test dest prepare failed
+	*simulateBTimout = true
+	srcKey = testNodeA.self + utils.RandString(10)
+	destKey = testNodeB.self + utils.RandString(10) // route to testNodeB, see mockPicker.PickNode
+	value = utils.RandString(10)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value, "ex", "1000"))
+	result = Rename(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey))
+	asserts.AssertErrReply(t, result, "ERR timeout")
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("EXISTS", srcKey))
+	asserts.AssertIntReply(t, result, 1)
+	result = testNodeA.db.Exec(conn, utils.ToCmdLine("TTL", srcKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+	result = testNodeB.db.Exec(conn, utils.ToCmdLine("EXISTS", destKey))
+	asserts.AssertIntReply(t, result, 0)
+	*simulateBTimout = false
+
+	// Copying to another database
+	srcKey = testNodeA.self + utils.RandString(10)
+	value = utils.RandString(10)
+	destKey = srcKey + utils.RandString(2)
+	testNodeA.db.Exec(conn, utils.ToCmdLine("SET", srcKey, value))
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey, destKey, "db", "1"))
+	asserts.AssertErrReply(t, result, copyToAnotherDBErr)
+
+	result = Copy(testNodeA, conn, utils.ToCmdLine("COPY", srcKey))
+	asserts.AssertErrReply(t, result, "ERR wrong number of arguments for 'copy' command")
+}
diff --git a/cluster/router.go b/cluster/router.go
index 9aea963..677d02c 100644
--- a/cluster/router.go
+++ b/cluster/router.go
@@ -25,6 +25,7 @@ func makeRouter() map[string]CmdFunc {
 	routerMap["type"] = defaultFunc
 	routerMap["rename"] = Rename
 	routerMap["renamenx"] = RenameNx
+	routerMap["copy"] = Copy
 
 	routerMap["set"] = defaultFunc
 	routerMap["setnx"] = defaultFunc
diff --git a/cluster/utils.go b/cluster/utils.go
index f9de730..fdeb669 100644
--- a/cluster/utils.go
+++ b/cluster/utils.go
@@ -42,7 +42,7 @@ func execSelect(c redis.Connection, args [][]byte) redis.Reply {
 	if err != nil {
 		return protocol.MakeErrReply("ERR invalid DB index")
 	}
-	if dbIndex >= config.Properties.Databases {
+	if dbIndex >= config.Properties.Databases || dbIndex < 0 {
 		return protocol.MakeErrReply("ERR DB index is out of range")
 	}
 	c.SelectDB(dbIndex)
diff --git a/commands.md b/commands.md
index 10b0a1a..adc4d5e 100644
--- a/commands.md
+++ b/commands.md
@@ -18,6 +18,7 @@
     - flushall
     - keys
     - bgrewriteaof
+    - copy
 - String
     - set
     - setnx
diff --git a/database/cluster_helper.go b/database/cluster_helper.go
index d5204d9..c85eafb 100644
--- a/database/cluster_helper.go
+++ b/database/cluster_helper.go
@@ -88,11 +88,52 @@ func execRenameNxTo(db *DB, args [][]byte) redis.Reply {
 	return execRenameTo(db, args)
 }
 
+// execCopyFrom just reply "OK" message, used for cluster.Copy
+func execCopyFrom(db *DB, args [][]byte) redis.Reply {
+	return protocol.MakeOkReply()
+}
+
+// execCopyTo accepts result of execDumpKey and load the dumped key
+// args format: key dumpCmd ttlCmd
+// execCopyTo may be partially successful, do not use it without transaction
+func execCopyTo(db *DB, args [][]byte) redis.Reply {
+	key := args[0]
+	dumpRawCmd, err := parser.ParseOne(args[1])
+	if err != nil {
+		return protocol.MakeErrReply("illegal dump cmd: " + err.Error())
+	}
+	dumpCmd, ok := dumpRawCmd.(*protocol.MultiBulkReply)
+	if !ok {
+		return protocol.MakeErrReply("dump cmd is not multi bulk reply")
+	}
+	dumpCmd.Args[1] = key // change key
+	ttlRawCmd, err := parser.ParseOne(args[2])
+	if err != nil {
+		return protocol.MakeErrReply("illegal ttl cmd: " + err.Error())
+	}
+	ttlCmd, ok := ttlRawCmd.(*protocol.MultiBulkReply)
+	if !ok {
+		return protocol.MakeErrReply("ttl cmd is not multi bulk reply")
+	}
+	ttlCmd.Args[1] = key
+	db.Remove(string(key))
+	dumpResult := db.execWithLock(dumpCmd.Args)
+	if protocol.IsErrorReply(dumpResult) {
+		return dumpResult
+	}
+	ttlResult := db.execWithLock(ttlCmd.Args)
+	if protocol.IsErrorReply(ttlResult) {
+		return ttlResult
+	}
+	return protocol.MakeOkReply()
+}
+
 func init() {
 	RegisterCommand("DumpKey", execDumpKey, writeAllKeys, undoDel, 2)
 	RegisterCommand("ExistIn", execExistIn, readAllKeys, nil, -1)
 	RegisterCommand("RenameFrom", execRenameFrom, readFirstKey, nil, 2)
 	RegisterCommand("RenameTo", execRenameTo, writeFirstKey, rollbackFirstKey, 4)
 	RegisterCommand("RenameNxTo", execRenameTo, writeFirstKey, rollbackFirstKey, 4)
-
+	RegisterCommand("CopyFrom", execCopyFrom, readFirstKey, nil, 2)
+	RegisterCommand("CopyTo", execCopyTo, writeFirstKey, rollbackFirstKey, 5)
 }
diff --git a/database/database.go b/database/database.go
index b330b30..0ab2cc5 100644
--- a/database/database.go
+++ b/database/database.go
@@ -122,6 +122,11 @@ func (mdb *MultiDB) Exec(c redis.Connection, cmdLine [][]byte) (result redis.Rep
 			return protocol.MakeArgNumErrReply("select")
 		}
 		return execSelect(c, mdb, cmdLine[1:])
+	} else if cmdName == "copy" {
+		if len(cmdLine) < 3 {
+			return protocol.MakeArgNumErrReply("copy")
+		}
+		return execCopy(mdb, c, cmdLine[1:])
 	}
 	// todo: support multi database transaction
 
@@ -151,7 +156,7 @@ func execSelect(c redis.Connection, mdb *MultiDB, args [][]byte) redis.Reply {
 	if err != nil {
 		return protocol.MakeErrReply("ERR invalid DB index")
 	}
-	if dbIndex >= len(mdb.dbSet) {
+	if dbIndex >= len(mdb.dbSet) || dbIndex < 0 {
 		return protocol.MakeErrReply("ERR DB index is out of range")
 	}
 	c.SelectDB(dbIndex)
diff --git a/database/keys.go b/database/keys.go
index 344e2bd..c345f84 100644
--- a/database/keys.go
+++ b/database/keys.go
@@ -11,6 +11,7 @@ import (
 	"github.com/hdt3213/godis/lib/wildcard"
 	"github.com/hdt3213/godis/redis/protocol"
 	"strconv"
+	"strings"
 	"time"
 )
 
@@ -308,6 +309,68 @@ func undoExpire(db *DB, args [][]byte) []CmdLine {
 	}
 }
 
+// execCopy usage: COPY source destination [DB destination-db] [REPLACE]
+// This command copies the value stored at the source key to the destination key.
+func execCopy(mdb *MultiDB, conn redis.Connection, args [][]byte) redis.Reply {
+	dbIndex := conn.GetDBIndex()
+	db := mdb.dbSet[dbIndex] // Current DB
+	replaceFlag := false
+	srcKey := string(args[0])
+	destKey := string(args[1])
+
+	// Parse options
+	if len(args) > 2 {
+		for i := 2; i < len(args); i++ {
+			arg := strings.ToLower(string(args[i]))
+			if arg == "db" {
+				if i+1 >= len(args) {
+					return &protocol.SyntaxErrReply{}
+				}
+				idx, err := strconv.Atoi(string(args[i+1]))
+				if err != nil {
+					return &protocol.SyntaxErrReply{}
+				}
+				if idx >= len(mdb.dbSet) || idx < 0 {
+					return protocol.MakeErrReply("ERR DB index is out of range")
+				}
+				dbIndex = idx
+				i++
+			} else if arg == "replace" {
+				replaceFlag = true
+			} else {
+				return &protocol.SyntaxErrReply{}
+			}
+		}
+	}
+
+	if srcKey == destKey && dbIndex == conn.GetDBIndex() {
+		return protocol.MakeErrReply("ERR source and destination objects are the same")
+	}
+
+	// source key does not exist
+	src, exists := db.GetEntity(srcKey)
+	if !exists {
+		return protocol.MakeIntReply(0)
+	}
+
+	destDB := mdb.dbSet[dbIndex]
+	if _, exists = destDB.GetEntity(destKey); exists != false {
+		// If destKey exists and there is no "replace" option
+		if replaceFlag == false {
+			return protocol.MakeIntReply(0)
+		}
+	}
+
+	destDB.PutEntity(destKey, src)
+	raw, exists := db.ttlMap.Get(srcKey)
+	if exists {
+		expire := raw.(time.Time)
+		destDB.Expire(destKey, expire)
+	}
+	mdb.aofHandler.AddAof(conn.GetDBIndex(), utils.ToCmdLine3("copy", args...))
+	return protocol.MakeIntReply(1)
+}
+
 func init() {
 	RegisterCommand("Del", execDel, writeAllKeys, undoDel, -2)
 	RegisterCommand("Expire", execExpire, writeFirstKey, undoExpire, 3)
diff --git a/database/keys_test.go b/database/keys_test.go
index 9f2539d..37b83cd 100644
--- a/database/keys_test.go
+++ b/database/keys_test.go
@@ -3,6 +3,7 @@ package database
 import (
 	"fmt"
 	"github.com/hdt3213/godis/lib/utils"
+	"github.com/hdt3213/godis/redis/connection"
 	"github.com/hdt3213/godis/redis/protocol"
 	"github.com/hdt3213/godis/redis/protocol/asserts"
 	"strconv"
@@ -205,3 +206,48 @@ func TestKeys(t *testing.T) {
 	result = testDB.Exec(nil, utils.ToCmdLine("keys", "?:*"))
 	asserts.AssertMultiBulkReplySize(t, result, 2)
 }
+
+func TestCopy(t *testing.T) {
+	testDB.Flush()
+	testMDB := NewStandaloneServer()
+	srcKey := utils.RandString(10)
+	destKey := "from:" + srcKey
+	value := utils.RandString(10)
+	conn := new(connection.FakeConn)
+
+	testMDB.Exec(conn, utils.ToCmdLine("set", srcKey, value))
+
+	// normal copy
+	result := testMDB.Exec(conn, utils.ToCmdLine("copy", srcKey, destKey))
+	asserts.AssertIntReply(t, result, 1)
+	result = testMDB.Exec(conn, utils.ToCmdLine("get", destKey))
+	asserts.AssertBulkReply(t, result, value)
+
+	// copy srcKey(DB 0) to destKey(DB 1)
+	testMDB.Exec(conn, utils.ToCmdLine("copy", srcKey, destKey, "db", "1"))
+	testMDB.Exec(conn, utils.ToCmdLine("select", "1"))
+	result = testMDB.Exec(conn, utils.ToCmdLine("get", destKey))
+	asserts.AssertBulkReply(t, result, value)
+
+	// test destKey already exists
+	testMDB.Exec(conn, utils.ToCmdLine("select", "0"))
+	result = testMDB.Exec(conn, utils.ToCmdLine("copy", srcKey, destKey))
+	asserts.AssertIntReply(t, result, 0)
+
+	// copy srcKey(DB 0) to destKey(DB 0) with "Replace"
+	value = "new:" + value
+	testMDB.Exec(conn, utils.ToCmdLine("set", srcKey, value)) // reset srcKey
+	result = testMDB.Exec(conn, utils.ToCmdLine("copy", srcKey, destKey, "replace"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testMDB.Exec(conn, utils.ToCmdLine("get", destKey))
+	asserts.AssertBulkReply(t, result, value)
+
+	// test copy expire time
+	testMDB.Exec(conn, utils.ToCmdLine("set", srcKey, value, "ex", "1000"))
+	result = testMDB.Exec(conn, utils.ToCmdLine("copy", srcKey, destKey, "replace"))
+	asserts.AssertIntReply(t, result, 1)
+	result = testMDB.Exec(conn, utils.ToCmdLine("ttl", srcKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+	result = testMDB.Exec(conn, utils.ToCmdLine("ttl", destKey))
+	asserts.AssertIntReplyGreaterThan(t, result, 0)
+}