diff --git a/src/Cnblogs.DashScope.AI/DashScopeChatClient.cs b/src/Cnblogs.DashScope.AI/DashScopeChatClient.cs
index 8b0012f..f28456f 100644
--- a/src/Cnblogs.DashScope.AI/DashScopeChatClient.cs
+++ b/src/Cnblogs.DashScope.AI/DashScopeChatClient.cs
@@ -459,12 +459,15 @@ private IEnumerable<TextChatMessage> ToTextChatMessages(
                         tools?.FindIndex(f => f.Function?.Name == c.Name) ?? -1,
                         new FunctionCall(c.Name, JsonSerializer.Serialize(c.Arguments, ToolCallJsonSerializerOptions))))
                 .ToList();
+
+            // function all array must be null when empty
+            // <400> InternalError.Algo.InvalidParameter: Empty tool_calls is not supported in message
             yield return new TextChatMessage(
                 from.Role.Value,
                 from.Text ?? string.Empty,
                 from.AuthorName,
                 null,
-                functionCall);
+                functionCall.Count > 0 ? functionCall : null);
         }
     }