diff --git a/library/think/File.php b/library/think/File.php
index 636a3430..932ad186 100644
--- a/library/think/File.php
+++ b/library/think/File.php
@@ -95,7 +95,8 @@ class File extends SplFileObject
 
     /**
      * 获取文件的哈希散列值
-     * @return $string
+     * @param string $type
+     * @return mixed $string
      */
     public function hash($type = 'sha1')
     {