diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index a5072fc8..ceb3d500 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -115,6 +115,7 @@ class Query
     {
         $this->connection = Db::connect($config);
         $this->setBuilder();
+        $this->prefix = $this->connection->getConfig('prefix');
         return $this;
     }