diff --git a/library/think/Request.php b/library/think/Request.php
index bc4386bc..dc5808d4 100644
--- a/library/think/Request.php
+++ b/library/think/Request.php
@@ -128,7 +128,9 @@ class Request
                 $this->$name = $item;
             }
         }
-        $this->filter = Config::get('default_filter');
+        if (is_null($this->filter)) {
+            $this->filter = Config::get('default_filter');
+        }
     }
 
     public function __call($method, $args)