diff --git a/README.md b/README.md
index 59d649c..118cab2 100644
--- a/README.md
+++ b/README.md
@@ -97,6 +97,8 @@ func producer() {
 
 ## Options
 
+### Consume Function
+
 ```go
 func (q *DelayQueue)WithCallback(callback CallbackFunc) *DelayQueue
 ```
@@ -113,12 +115,21 @@ queue.WithCallback(func(payload string) bool {
 })
 ```
 
+### Logger
+
 ```go
-func (q *DelayQueue)WithLogger(logger *log.Logger) *DelayQueue
+func (q *DelayQueue)WithLogger(logger Logger) *DelayQueue
 ```
 
-WithLogger customizes logger for queue
+WithLogger customizes logger for queue. Logger should implemented the following interface:
 
+```go
+type Logger interface {
+	Printf(format string, v ...interface{})
+}
+```
+
+### Concurrent
 
 ```go
 func (q *DelayQueue)WithConcurrent(c uint) *DelayQueue
@@ -126,12 +137,16 @@ func (q *DelayQueue)WithConcurrent(c uint) *DelayQueue
 
 WithConcurrent sets the number of concurrent consumers
 
+### Polling Interval
+
 ```go
 func (q *DelayQueue)WithFetchInterval(d time.Duration) *DelayQueue
 ```
 
 WithFetchInterval customizes the interval at which consumer fetch message from redis
 
+### Timeout
+
 ```go
 func (q *DelayQueue)WithMaxConsumeDuration(d time.Duration) *DelayQueue
 ```
@@ -141,12 +156,16 @@ WithMaxConsumeDuration customizes max consume duration
 If no acknowledge received within WithMaxConsumeDuration after message delivery, DelayQueue will try to deliver this
 message again
 
+### Max Processing Limit
+
 ```go
 func (q *DelayQueue)WithFetchLimit(limit uint) *DelayQueue
 ```
 
 WithFetchLimit limits the max number of unack (processing) messages
 
+### Hash Tag
+
 ```go
 UseHashTagKey()
 ```
@@ -159,6 +178,8 @@ WARNING! CHANGING(add or remove) this option will cause DelayQueue failing to re
 
 > see more:  https://redis.io/docs/reference/cluster-spec/#hash-tags
 
+### Default Retry Count
+
 ```go
 WithDefaultRetryCount(count uint)  *DelayQueue
 ```
@@ -167,6 +188,12 @@ WithDefaultRetryCount customizes the max number of retry, it effects of messages
 
 use WithRetryCount during DelayQueue.SendScheduleMsg or DelayQueue.SendDelayMsg to specific retry count of particular message
 
+```go
+queue.SendDelayMsg(msg, time.Hour, delayqueue.WithRetryCount(3))
+```
+
+### Script Preload
+
 ```go
 (q *DelayQueue) WithScriptPreload(flag bool) *DelayQueue
 ```
diff --git a/README_CN.md b/README_CN.md
index dcaf255..bf32638 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -92,6 +92,8 @@ func producer() {
 
 ## 选项
 
+### 回调函数
+
 ```go
 func (q *DelayQueue)WithCallback(callback CallbackFunc) *DelayQueue
 ```
@@ -107,12 +109,21 @@ queue.WithCallback(func(payload string) bool {
 })
 ```
 
+### 日志
+
 ```go
 func (q *DelayQueue)WithLogger(logger *log.Logger) *DelayQueue
 ```
 
-为 DelayQueue 设置 logger
+为 DelayQueue 设置 logger, logger 需要实现下面的接口：
 
+```go
+type Logger interface {
+	Printf(format string, v ...interface{})
+}
+```
+
+### 并发数
 
 ```go
 func (q *DelayQueue)WithConcurrent(c uint) *DelayQueue 
@@ -120,23 +131,31 @@ func (q *DelayQueue)WithConcurrent(c uint) *DelayQueue
 
 设置消费者并发数
 
+### 轮询间隔
+
 ```go
 func (q *DelayQueue)WithFetchInterval(d time.Duration) *DelayQueue
 ```
 
 设置消费者从 Redis 拉取消息的时间间隔
 
+### 消费超时
+
 ```go
 func (q *DelayQueue)WithMaxConsumeDuration(d time.Duration) *DelayQueue
 ```
 
 设置最长消费时间。若拉取消息后超出 MaxConsumeDuration 时限仍未返回 ACK 则认为消费失败，DelayQueue 会重新投递此消息。
 
+### 最大处理中消息数
+
 ```go
 func (q *DelayQueue)WithFetchLimit(limit uint) *DelayQueue
 ```
 
-FetchLimit 限制消费者从 Redis 中拉取的消息数目，即单个消费者正在处理中的消息数不会超过 FetchLimit
+单个消费者正在处理中的消息数不会超过 FetchLimit
+
+### 启用 HashTag
 
 ```go
 UseHashTagKey()
@@ -150,6 +169,8 @@ UseHashTagKey() 会在 Redis Key 上添加 hash tag 确保同一个队列的所
 
 see more: https://redis.io/docs/reference/cluster-spec/#hash-tags
 
+### 设置默认重试次数
+
 ```go
 WithDefaultRetryCount(count uint)
 ```
@@ -158,6 +179,12 @@ WithDefaultRetryCount(count uint)
 
 在调用  DelayQueue.SendScheduleMsg or DelayQueue.SendDelayMsg 发送消息时，可以调用 WithRetryCount 为这条消息单独指定重试次数。
 
+```go
+queue.SendDelayMsg(msg, time.Hour, delayqueue.WithRetryCount(3))
+```
+
+### 预加载脚本
+
 ```go
 (q *DelayQueue) WithScriptPreload(flag bool) *DelayQueue
 ```
diff --git a/delayqueue.go b/delayqueue.go
index f35e716..de25d90 100644
--- a/delayqueue.go
+++ b/delayqueue.go
@@ -27,7 +27,7 @@ type DelayQueue struct {
 	garbageKey         string // set: message id
 	useHashTag         bool
 	ticker             *time.Ticker
-	logger             *log.Logger
+	logger             Logger
 	close              chan struct{}
 	running            int32
 	maxConsumeDuration time.Duration // default 5 seconds
@@ -82,6 +82,11 @@ type RedisCli interface {
 	EvalSha(sha1 string, keys []string, args []interface{}) (interface{}, error)
 }
 
+// Logger is an abstraction of logging system
+type Logger interface {
+	Printf(format string, v ...interface{})
+}
+
 type hashTagKeyOpt int
 
 // CallbackFunc receives and consumes messages
@@ -153,7 +158,7 @@ func (q *DelayQueue) WithCallback(callback CallbackFunc) *DelayQueue {
 }
 
 // WithLogger customizes logger for queue
-func (q *DelayQueue) WithLogger(logger *log.Logger) *DelayQueue {
+func (q *DelayQueue) WithLogger(logger Logger) *DelayQueue {
 	q.logger = logger
 	return q
 }