diff --git a/apps/application/flow/step_node/ai_chat_step_node/impl/base_chat_node.py b/apps/application/flow/step_node/ai_chat_step_node/impl/base_chat_node.py
index 59f8a5fbb12..a87c9123e82 100644
--- a/apps/application/flow/step_node/ai_chat_step_node/impl/base_chat_node.py
+++ b/apps/application/flow/step_node/ai_chat_step_node/impl/base_chat_node.py
@@ -224,7 +224,7 @@ def execute(self, model_id, system, prompt, dialogue_number, history_chat_record
         )
         if mcp_result:
             return mcp_result
-
+        message_list = [SystemMessage(system)] + message_list
         if stream:
             r = chat_model.stream(message_list)
             return NodeResult({'result': r, 'chat_model': chat_model, 'message_list': message_list,