diff --git a/src/llamafactory/chat/hf_engine.py b/src/llamafactory/chat/hf_engine.py
index 90fe1b81..1ef99d9f 100644
--- a/src/llamafactory/chat/hf_engine.py
+++ b/src/llamafactory/chat/hf_engine.py
@@ -59,6 +59,7 @@ class HuggingfaceEngine(BaseEngine):
             messages[0]["content"] = "<image>" + messages[0]["content"]
 
         paired_messages = messages + [{"role": "assistant", "content": ""}]
+        system = system or generating_args["default_system"]
         prompt_ids, _ = template.encode_oneturn(
             tokenizer=tokenizer, messages=paired_messages, system=system, tools=tools
         )
diff --git a/src/llamafactory/chat/vllm_engine.py b/src/llamafactory/chat/vllm_engine.py
index ba0cc1b3..2e8ecd0c 100644
--- a/src/llamafactory/chat/vllm_engine.py
+++ b/src/llamafactory/chat/vllm_engine.py
@@ -96,6 +96,7 @@ class VllmEngine(BaseEngine):
             messages[0]["content"] = "<image>" * self.image_feature_size + messages[0]["content"]
 
         paired_messages = messages + [{"role": "assistant", "content": ""}]
+        system = system or self.generating_args["default_system"]
         prompt_ids, _ = self.template.encode_oneturn(
             tokenizer=self.tokenizer, messages=paired_messages, system=system, tools=tools
         )
diff --git a/src/llamafactory/hparams/generating_args.py b/src/llamafactory/hparams/generating_args.py
index e792c003..0ee17d1a 100644
--- a/src/llamafactory/hparams/generating_args.py
+++ b/src/llamafactory/hparams/generating_args.py
@@ -1,5 +1,5 @@
 from dataclasses import asdict, dataclass, field
-from typing import Any, Dict
+from typing import Any, Dict, Optional
 
 
 @dataclass
@@ -46,6 +46,10 @@ class GeneratingArguments:
         default=1.0,
         metadata={"help": "Exponential penalty to the length that is used with beam-based generation."},
     )
+    default_system: Optional[str] = field(
+        default=None,
+        metadata={"help": "Default system message to use in chat completion."},
+    )
 
     def to_dict(self) -> Dict[str, Any]:
         args = asdict(self)