diff --git a/library/think/File.php b/library/think/File.php
index 580cb7dd..fc888b10 100644
--- a/library/think/File.php
+++ b/library/think/File.php
@@ -151,7 +151,7 @@ class File extends SplFileObject
                         $savename = substr($sha1, 0, 2) . DS . substr($sha1, 2);
                         break;
                     case 'date':
-                        $savename = date('Y-m-d') . DS . md5(microtime(true));
+                        $savename = date('Ymd') . DS . md5(microtime(true));
                         break;
                     default:
                         $savename = call_user_func($this->rule);