diff --git a/lmdeploy/serve/async_engine.py b/lmdeploy/serve/async_engine.py
index 2a0c3f18ce..78574a38b1 100644
--- a/lmdeploy/serve/async_engine.py
+++ b/lmdeploy/serve/async_engine.py
@@ -223,9 +223,10 @@ def __call__(self,
         """Inference a batch of prompts.
 
         Args:
-            prompts (List[str] | str | List[Dict] | List[List[Dict]]]): a batch of
-                prompts. It accepts: string prompt, a list of string prompts,
-                a chat history in OpenAI format or a list of chat history.
+            prompts (List[str] | str | List[Dict] | List[List[Dict]]]): a
+            batch of prompts. It accepts: string prompt, a list of string
+            prompts, a chat history in OpenAI format or a list of chat
+            history.
             gen_config (GenerationConfig | None): a instance of
                 GenerationConfig. Default to None.
             do_preprocess (bool): whether pre-process the messages. Default to
@@ -297,9 +298,10 @@ def batch_infer(self,
         """Inference a batch of prompts.
 
         Args:
-            prompts (List[str] | str | List[Dict] | List[List[Dict]]]): a batch of
-                prompts. It accepts: string prompt, a list of string prompts,
-                a chat history in OpenAI format or a list of chat history.
+            prompts (List[str] | str | List[Dict] | List[List[Dict]]]): a
+            batch of prompts. It accepts: string prompt, a list of string
+            prompts, a chat history in OpenAI format or a list of chat
+            history.
             gen_config (GenerationConfig | None): a instance of or a list of
                 GenerationConfig. Default to None.
             do_preprocess (bool): whether pre-process the messages. Default to
@@ -374,9 +376,10 @@ def stream_infer(
         """Inference a batch of prompts with stream mode.
 
         Args:
-            prompts (List[str] | str | List[Dict] | List[List[Dict]]]): a batch of
-                prompts. It accepts: string prompt, a list of string prompts,
-                a chat history in OpenAI format or a list of chat history.
+            prompts (List[str] | str | List[Dict] | List[List[Dict]]]):a
+            batch of prompts. It accepts: string prompt, a list of string
+            prompts, a chat history in OpenAI format or a list of chat
+            history.
             gen_config (GenerationConfig | None): a instance of or a list of
                 GenerationConfig. Default to None.
             do_preprocess (bool): whether pre-process the messages. Default to