diff --git a/docs/parameters.md b/docs/parameters.md
index 245eec83f..28a66b72c 100644
--- a/docs/parameters.md
+++ b/docs/parameters.md
@@ -8,6 +8,8 @@ When using FastDeploy to deploy models (including offline inference and service
 |:--------------|:----|:-----------|
 | ```port``` | `int` | Only required for service deployment, HTTP service port number, default: 8000 |
 | ```metrics_port``` | `int` | Only required for service deployment, metrics monitoring port number, default: 8001 |
+| ```max_waiting_time``` | `int` | Only required for service deployment, maximum wait time for establishing a connection upon service request. Default: -1 (indicates no wait time limit).|
+| ```max_concurrency```  | `int` | Only required for service deployment, the actual number of connections established by the service, default 512 |
 | ```engine_worker_queue_port``` | `int` | FastDeploy internal engine communication port, default: 8002 |
 | ```cache_queue_port``` | `int` | FastDeploy internal KVCache process communication port, default: 8003 |
 | ```max_model_len``` | `int` | Default maximum supported context length for inference, default: 2048 |
diff --git a/docs/zh/parameters.md b/docs/zh/parameters.md
index 244d78ab7..177a2d97b 100644
--- a/docs/zh/parameters.md
+++ b/docs/zh/parameters.md
@@ -6,6 +6,8 @@
 |:-----------------------------------|:----------| :----- |
 | ```port```                         | `int`       | 仅服务化部署需配置，服务HTTP请求端口号，默认8000 |
 | ```metrics_port```                 | `int`       | 仅服务化部署需配置，服务监控Metrics端口号，默认8001 |
+| ```max_waiting_time```             | `int`       | 仅服务化部署需配置，服务请求建立连接最大等待时间，默认-1 表示无等待时间限制|
+| ```max_concurrency```              | `int`       | 仅服务化部署需配置，服务实际建立连接数目，默认512 |
 | ```engine_worker_queue_port```     | `int`       | FastDeploy内部引擎进程通信端口, 默认8002 |
 | ```cache_queue_port```             | `int`       | FastDeploy内部KVCache进程通信端口, 默认8003 |
 | ```max_model_len```                | `int`       | 推理默认最大支持上下文长度，默认2048 |
diff --git a/fastdeploy/entrypoints/engine_client.py b/fastdeploy/entrypoints/engine_client.py
index d5d051c8c..92d7ac007 100644
--- a/fastdeploy/entrypoints/engine_client.py
+++ b/fastdeploy/entrypoints/engine_client.py
@@ -21,12 +21,13 @@ import numpy as np
 
 from fastdeploy import envs
 from fastdeploy.engine.config import ModelConfig
+from fastdeploy.envs import FD_SUPPORT_MAX_CONNECTIONS
 from fastdeploy.input.preprocess import InputPreprocessor
 from fastdeploy.inter_communicator import IPCSignal, ZmqClient
 from fastdeploy.metrics.work_metrics import work_process_metrics
 from fastdeploy.multimodal.registry import MultimodalRegistry
 from fastdeploy.platforms import current_platform
-from fastdeploy.utils import EngineError, api_server_logger
+from fastdeploy.utils import EngineError, StatefulSemaphore, api_server_logger
 
 
 class EngineClient:
@@ -47,6 +48,7 @@ class EngineClient:
         reasoning_parser=None,
         data_parallel_size=1,
         enable_logprob=False,
+        workers=1,
     ):
         import fastdeploy.model_executor.models  # noqa: F401
 
@@ -77,7 +79,7 @@ class EngineClient:
             suffix=pid,
             create=False,
         )
-
+        self.semaphore = StatefulSemaphore((FD_SUPPORT_MAX_CONNECTIONS + workers - 1) // workers)
         model_weights_status = np.zeros([1], dtype=np.int32)
         self.model_weights_status_signal = IPCSignal(
             name="model_weights_status",
diff --git a/fastdeploy/entrypoints/openai/api_server.py b/fastdeploy/entrypoints/openai/api_server.py
index 0f9467c54..23f4a061a 100644
--- a/fastdeploy/entrypoints/openai/api_server.py
+++ b/fastdeploy/entrypoints/openai/api_server.py
@@ -14,15 +14,17 @@
 # limitations under the License.
 """
 
+import asyncio
 import os
 import threading
 import time
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
 from multiprocessing import current_process
 
 import uvicorn
 import zmq
-from fastapi import FastAPI, Request
+from fastapi import FastAPI, HTTPException, Request
 from fastapi.responses import JSONResponse, Response, StreamingResponse
 from prometheus_client import CONTENT_TYPE_LATEST
 
@@ -49,6 +51,7 @@ from fastdeploy.metrics.trace_util import fd_start_span, inject_to_metadata, ins
 from fastdeploy.plugins.model_register import load_model_register_plugins
 from fastdeploy.utils import (
     FlexibleArgumentParser,
+    StatefulSemaphore,
     api_server_logger,
     console_logger,
     is_port_available,
@@ -61,6 +64,13 @@ parser.add_argument("--host", default="0.0.0.0", type=str, help="host to the htt
 parser.add_argument("--workers", default=1, type=int, help="number of workers")
 parser.add_argument("--metrics-port", default=8001, type=int, help="port for metrics server")
 parser.add_argument("--controller-port", default=-1, type=int, help="port for controller server")
+parser.add_argument(
+    "--max-waiting-time",
+    default=-1,
+    type=int,
+    help="max waiting time for connection, if set value -1 means no waiting time limit",
+)
+parser.add_argument("--max-concurrency", default=512, type=int, help="max concurrency")
 parser = EngineArgs.add_cli_args(parser)
 args = parser.parse_args()
 args.model = retrive_model_from_server(args.model, args.revision)
@@ -92,6 +102,12 @@ def load_engine():
     return engine
 
 
+app = FastAPI()
+
+MAX_CONCURRENT_CONNECTIONS = (args.max_concurrency + args.workers - 1) // args.workers
+connection_semaphore = StatefulSemaphore(MAX_CONCURRENT_CONNECTIONS)
+
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     """
@@ -117,10 +133,11 @@ async def lifespan(app: FastAPI):
         args.reasoning_parser,
         args.data_parallel_size,
         args.enable_logprob,
+        args.workers,
     )
     app.state.dynamic_load_weight = args.dynamic_load_weight
-    chat_handler = OpenAIServingChat(engine_client, pid, args.ips)
-    completion_handler = OpenAIServingCompletion(engine_client, pid, args.ips)
+    chat_handler = OpenAIServingChat(engine_client, pid, args.ips, args.max_waiting_time)
+    completion_handler = OpenAIServingCompletion(engine_client, pid, args.ips, args.max_waiting_time)
     engine_client.create_zmq_client(model=pid, mode=zmq.PUSH)
     engine_client.pid = pid
     app.state.engine_client = engine_client
@@ -142,6 +159,21 @@ app = FastAPI(lifespan=lifespan)
 instrument(app)
 
 
+@asynccontextmanager
+async def connection_manager():
+    """
+    async context manager for connection manager
+    """
+    try:
+        await asyncio.wait_for(connection_semaphore.acquire(), timeout=0.001)
+        yield
+    except asyncio.TimeoutError:
+        api_server_logger.info(f"Reach max request release: {connection_semaphore.status()}")
+        if connection_semaphore.locked():
+            connection_semaphore.release()
+        raise HTTPException(status_code=429, detail="Too many requests")
+
+
 # TODO 传递真实引擎值 通过pid 获取状态
 @app.get("/health")
 def health(request: Request) -> Response:
@@ -195,6 +227,22 @@ def ping(raw_request: Request) -> Response:
     return health(raw_request)
 
 
+def wrap_streaming_generator(original_generator: AsyncGenerator):
+    """
+    Wrap an async generator to release the connection semaphore when the generator is finished.
+    """
+
+    async def wrapped_generator():
+        try:
+            async for chunk in original_generator:
+                yield chunk
+        finally:
+            api_server_logger.debug(f"release: {connection_semaphore.status()}")
+            connection_semaphore.release()
+
+    return wrapped_generator
+
+
 @app.post("/v1/chat/completions")
 async def create_chat_completion(request: ChatCompletionRequest):
     """
@@ -204,16 +252,23 @@ async def create_chat_completion(request: ChatCompletionRequest):
         status, msg = app.state.engine_client.is_workers_alive()
         if not status:
             return JSONResponse(content={"error": "Worker Service Not Healthy"}, status_code=304)
-    inject_to_metadata(request)
-    generator = await app.state.chat_handler.create_chat_completion(request)
+    try:
+        async with connection_manager():
+            inject_to_metadata(request)
+            generator = await app.state.chat_handler.create_chat_completion(request)
+            if isinstance(generator, ErrorResponse):
+                connection_semaphore.release()
+                return JSONResponse(content={"detail": generator.model_dump()}, status_code=generator.code)
+            elif isinstance(generator, ChatCompletionResponse):
+                connection_semaphore.release()
+                return JSONResponse(content=generator.model_dump())
+            else:
+                wrapped_generator = wrap_streaming_generator(generator)
+                return StreamingResponse(content=wrapped_generator(), media_type="text/event-stream")
 
-    if isinstance(generator, ErrorResponse):
-        return JSONResponse(content=generator.model_dump(), status_code=generator.code)
-
-    elif isinstance(generator, ChatCompletionResponse):
-        return JSONResponse(content=generator.model_dump())
-
-    return StreamingResponse(content=generator, media_type="text/event-stream")
+    except HTTPException as e:
+        api_server_logger.error(f"Error in chat completion: {str(e)}")
+        return JSONResponse(status_code=e.status_code, content={"detail": e.detail})
 
 
 @app.post("/v1/completions")
@@ -225,14 +280,20 @@ async def create_completion(request: CompletionRequest):
         status, msg = app.state.engine_client.is_workers_alive()
         if not status:
             return JSONResponse(content={"error": "Worker Service Not Healthy"}, status_code=304)
-
-    generator = await app.state.completion_handler.create_completion(request)
-    if isinstance(generator, ErrorResponse):
-        return JSONResponse(content=generator.model_dump(), status_code=generator.code)
-    elif isinstance(generator, CompletionResponse):
-        return JSONResponse(content=generator.model_dump())
-
-    return StreamingResponse(content=generator, media_type="text/event-stream")
+    try:
+        async with connection_manager():
+            generator = await app.state.completion_handler.create_completion(request)
+            if isinstance(generator, ErrorResponse):
+                connection_semaphore.release()
+                return JSONResponse(content=generator.model_dump(), status_code=generator.code)
+            elif isinstance(generator, CompletionResponse):
+                connection_semaphore.release()
+                return JSONResponse(content=generator.model_dump())
+            else:
+                wrapped_generator = wrap_streaming_generator(generator)
+                return StreamingResponse(content=wrapped_generator(), media_type="text/event-stream")
+    except HTTPException as e:
+        return JSONResponse(status_code=e.status_code, content={"detail": e.detail})
 
 
 @app.get("/update_model_weight")
diff --git a/fastdeploy/entrypoints/openai/serving_chat.py b/fastdeploy/entrypoints/openai/serving_chat.py
index 3e74c89df..8d8d4b98d 100644
--- a/fastdeploy/entrypoints/openai/serving_chat.py
+++ b/fastdeploy/entrypoints/openai/serving_chat.py
@@ -49,10 +49,11 @@ class OpenAIServingChat:
     OpenAI-style chat completions serving
     """
 
-    def __init__(self, engine_client, pid, ips):
+    def __init__(self, engine_client, pid, ips, max_waiting_time):
         self.engine_client = engine_client
         self.pid = pid
         self.master_ip = ips
+        self.max_waiting_time = max_waiting_time
         self.host_ip = get_host_ip()
         if self.master_ip is not None:
             if isinstance(self.master_ip, list):
@@ -93,6 +94,14 @@ class OpenAIServingChat:
             return ErrorResponse(code=400, message=str(e))
 
         del current_req_dict
+        try:
+            api_server_logger.debug(f"{self.engine_client.semaphore.status()}")
+            if self.max_waiting_time < 0:
+                await self.engine_client.semaphore.acquire()
+            else:
+                await asyncio.wait_for(self.engine_client.semaphore.acquire(), timeout=self.max_waiting_time)
+        except Exception:
+            return ErrorResponse(code=408, message=f"Request queued time exceed {self.max_waiting_time}")
 
         if request.stream:
             return self.chat_completion_stream_generator(request, request_id, request.model, prompt_token_ids)
@@ -310,6 +319,8 @@ class OpenAIServingChat:
             yield f"data: {error_data}\n\n"
         finally:
             dealer.close()
+            self.engine_client.semaphore.release()
+            api_server_logger.info(f"release {self.engine_client.semaphore.status()}")
             yield "data: [DONE]\n\n"
 
     async def chat_completion_full_generator(
@@ -383,6 +394,7 @@ class OpenAIServingChat:
                 if task_is_finished:
                     break
         finally:
+            self.engine_client.semaphore.release()
             dealer.close()
 
         choices = []
diff --git a/fastdeploy/entrypoints/openai/serving_completion.py b/fastdeploy/entrypoints/openai/serving_completion.py
index 2a0e5e9ec..43766f27f 100644
--- a/fastdeploy/entrypoints/openai/serving_completion.py
+++ b/fastdeploy/entrypoints/openai/serving_completion.py
@@ -40,11 +40,12 @@ from fastdeploy.worker.output import LogprobsLists
 
 
 class OpenAIServingCompletion:
-    def __init__(self, engine_client, pid, ips):
+    def __init__(self, engine_client, pid, ips, max_waiting_time):
         self.engine_client = engine_client
         self.pid = pid
         self.master_ip = ips
         self.host_ip = get_host_ip()
+        self.max_waiting_time = max_waiting_time
         if self.master_ip is not None:
             if isinstance(self.master_ip, list):
                 self.master_ip = self.master_ip[0]
@@ -114,6 +115,14 @@ class OpenAIServingCompletion:
 
                 del current_req_dict
 
+            try:
+                if self.max_waiting_time < 0:
+                    await self.engine_client.semaphore.acquire()
+                else:
+                    await asyncio.wait_for(self.engine_client.semaphore.acquire(), timeout=self.max_waiting_time)
+            except Exception:
+                return ErrorResponse(code=408, message=f"Request queued time exceed {self.max_waiting_time}")
+
             if request.stream:
                 return self.completion_stream_generator(
                     request=request,
@@ -221,6 +230,7 @@ class OpenAIServingCompletion:
             api_server_logger.error(f"Error in completion_full_generator: {e}", exc_info=True)
             raise
         finally:
+            self.engine_client.semaphore.release()
             if dealer is not None:
                 dealer.close()
 
@@ -371,6 +381,7 @@ class OpenAIServingCompletion:
             yield f"data: {ErrorResponse(message=str(e), code=400).model_dump_json(exclude_unset=True)}\n\n"
         finally:
             del request
+            self.engine_client.semaphore.release()
             if dealer is not None:
                 dealer.close()
             yield "data: [DONE]\n\n"
diff --git a/fastdeploy/envs.py b/fastdeploy/envs.py
index 6d17ac005..d9f5beb9c 100644
--- a/fastdeploy/envs.py
+++ b/fastdeploy/envs.py
@@ -84,6 +84,8 @@ environment_variables: dict[str, Callable[[], Any]] = {
     "FD_PLUGINS": lambda: None if "FD_PLUGINS" not in os.environ else os.environ["FD_PLUGINS"].split(","),
     # set trace attribute job_id.
     "FD_JOB_ID": lambda: os.getenv("FD_JOB_ID"),
+    # support max connections
+    "FD_SUPPORT_MAX_CONNECTIONS": lambda: 768,
 }
 
 
diff --git a/fastdeploy/utils.py b/fastdeploy/utils.py
index 0eed87c55..27783b428 100644
--- a/fastdeploy/utils.py
+++ b/fastdeploy/utils.py
@@ -15,6 +15,7 @@
 """
 
 import argparse
+import asyncio
 import codecs
 import importlib
 import logging
@@ -304,6 +305,16 @@ def set_random_seed(seed: int) -> None:
         paddle.seed(seed)
 
 
+def get_limited_max_value(max_value):
+    def validator(value):
+        value = float(value)
+        if value > max_value:
+            raise argparse.ArgumentTypeError(f"The value cannot exceed {max_value}")
+        return value
+
+    return validator
+
+
 def download_model(url, output_dir, temp_tar):
     """
     下载模型，并将其解压到指定目录。
@@ -653,6 +664,61 @@ def deprecated_kwargs_warning(**kwargs):
             console_logger.warning(f"Deprecated argument is detected: {arg}, which may be removed later")
 
 
+class StatefulSemaphore:
+    __slots__ = ("_semaphore", "_max_value", "_acquired_count", "_last_reset")
+
+    """
+    StatefulSemaphore is a class that wraps an asyncio.Semaphore and provides additional stateful information.
+    """
+
+    def __init__(self, value: int):
+        """
+        StatefulSemaphore constructor
+        """
+        if value < 0:
+            raise ValueError("Value must be non-negative.")
+        self._semaphore = asyncio.Semaphore(value)
+        self._max_value = value
+        self._acquired_count = 0
+        self._last_reset = time.monotonic()
+
+    async def acquire(self):
+        await self._semaphore.acquire()
+        self._acquired_count += 1
+
+    def release(self):
+        self._semaphore.release()
+
+        self._acquired_count = max(0, self._acquired_count - 1)
+
+    def locked(self) -> bool:
+        return self._semaphore.locked()
+
+    @property
+    def available(self) -> int:
+        return self._max_value - self._acquired_count
+
+    @property
+    def acquired(self) -> int:
+        return self._acquired_count
+
+    @property
+    def max_value(self) -> int:
+        return self._max_value
+
+    @property
+    def uptime(self) -> float:
+        return time.monotonic() - self._last_reset
+
+    def status(self) -> dict:
+        return {
+            "available": self.available,
+            "acquired": self.acquired,
+            "max_value": self.max_value,
+            "uptime": round(self.uptime, 2),
+        }
+
+
 llm_logger = get_logger("fastdeploy", "fastdeploy.log")
 data_processor_logger = get_logger("data_processor", "data_processor.log")
 scheduler_logger = get_logger("scheduler", "scheduler.log")