diff --git a/autogen/function_utils.py b/autogen/function_utils.py
index dd225fd4719..6b9b6f5b129 100644
--- a/autogen/function_utils.py
+++ b/autogen/function_utils.py
@@ -353,4 +353,4 @@ def serialize_to_str(x: Any) -> str:
     elif isinstance(x, BaseModel):
         return model_dump_json(x)
     else:
-        return json.dumps(x)
+        return json.dumps(x, ensure_ascii=False)
diff --git a/test/test_function_utils.py b/test/test_function_utils.py
index adddbf32e26..0475044b49f 100644
--- a/test/test_function_utils.py
+++ b/test/test_function_utils.py
@@ -391,6 +391,10 @@ async def f(
     assert actual[1] == "EUR"
 
 
+def test_serialize_to_str_with_nonascii() -> None:
+    assert serialize_to_str("中文") == "中文"
+
+
 def test_serialize_to_json() -> None:
     assert serialize_to_str("abc") == "abc"
     assert serialize_to_str(123) == "123"