diff --git a/library/think/Db.php b/library/think/Db.php
index e239fd4e..8fa799eb 100644
--- a/library/think/Db.php
+++ b/library/think/Db.php
@@ -82,10 +82,9 @@ class Db
                 Log::record('[ DB ] INIT ' . $options['type'], 'info');
             }
             if (true === $name) {
-                return new $class($options);
-            } else {
-                self::$instance[$name] = new $class($options);
+                $name = md5(serialize($config));
             }
+            self::$instance[$name] = new $class($options);
         }
         return self::$instance[$name];
     }