diff --git a/fastdeploy/input/preprocess.py b/fastdeploy/input/preprocess.py
index 48626f380..16615599b 100644
--- a/fastdeploy/input/preprocess.py
+++ b/fastdeploy/input/preprocess.py
@@ -76,7 +76,9 @@ class InputPreprocessor:
                 load_reasoning_parser_plugins,
             )
 
-            reasoning_parser_obj = load_reasoning_parser_plugins()
+            custom_reasoning_parser = load_reasoning_parser_plugins()
+            if self.reasoning_parser == "custom_reasoning_parser":
+                reasoning_parser_obj = custom_reasoning_parser
         except:
             if self.reasoning_parser:
                 reasoning_parser_obj = ReasoningParserManager.get_reasoning_parser(self.reasoning_parser)