diff --git a/pilot/scene/base_chat.py b/pilot/scene/base_chat.py
index 0c8abac4f..13fbf2708 100644
--- a/pilot/scene/base_chat.py
+++ b/pilot/scene/base_chat.py
@@ -125,10 +125,16 @@ class BaseChat(ABC):
             current_prompt = self.prompt_template.format(**input_values)
             self.current_message.add_system_message(current_prompt)
 
+        llm_messages = self.generate_llm_messages()
+        if not CFG.NEW_SERVER_MODE:
+            # Not new server mode, we convert the message format(List[ModelMessage]) to list of dict
+            # fix the error of "Object of type ModelMessage is not JSON serializable" when passing the payload to request.post
+            llm_messages = list(map(lambda m: m.dict(), llm_messages))
+
         payload = {
             "model": self.llm_model,
             "prompt": self.generate_llm_text(),
-            "messages": self.generate_llm_messages(),
+            "messages": llm_messages,
             "temperature": float(self.prompt_template.temperature),
             "max_new_tokens": int(self.prompt_template.max_new_tokens),
             "stop": self.prompt_template.sep,
diff --git a/pilot/server/chat_adapter.py b/pilot/server/chat_adapter.py
index 0ca8f97da..d47bc6cc8 100644
--- a/pilot/server/chat_adapter.py
+++ b/pilot/server/chat_adapter.py
@@ -28,6 +28,15 @@ class BaseChatAdpter:
         messages = params.get("messages")
         # Some model scontext to dbgpt server
         model_context = {"prompt_echo_len_char": -1}
+
+        if messages:
+            # Dict message to ModelMessage
+            messages = [
+                m if isinstance(m, ModelMessage) else ModelMessage(**m)
+                for m in messages
+            ]
+            params["messages"] = messages
+
         if not conv or not messages:
             # Nothing to do
             print(