diff --git a/library/think/Db.php b/library/think/Db.php
index 832ed66d..a8a86972 100644
--- a/library/think/Db.php
+++ b/library/think/Db.php
@@ -28,23 +28,30 @@ class Db
      * @static
      * @access public
      * @param mixed $config 连接配置
-     * @return Object 返回数据库驱动类
+     * @param bool|string $name 连接标识 true 强制重新连接
+     * @return \think\db\Connection
      */
-    public static function connect($config = [])
+    public static function connect($config = [], $name = false)
     {
-        $md5 = md5(serialize($config));
-        if (!isset(self::$instances[$md5])) {
+        if (false === $name) {
+            $name = md5(serialize($config));
+        }
+        if (true === $name || !isset(self::$instances[$name])) {
             // 解析连接参数 支持数组和字符串
             $options = self::parseConfig($config);
             if (empty($options['type'])) {
                 throw new Exception('db type error');
             }
-            $class                 = (!empty($options['namespace']) ? $options['namespace'] : '\\think\\db\\connector\\') . ucwords($options['type']);
-            self::$instances[$md5] = new $class($options);
+            $class = (!empty($options['namespace']) ? $options['namespace'] : '\\think\\db\\connector\\') . ucwords($options['type']);
             // 记录初始化信息
             APP_DEBUG && Log::record('[ DB ] INIT ' . $options['type'] . ':' . var_export($options, true), 'info');
+            if (true === $name) {
+                return new $class($options);
+            } else {
+                self::$instances[$name] = new $class($options);
+            }
         }
-        return self::$instances[$md5];
+        return self::$instances[$name];
     }
 
     /**
diff --git a/library/think/Model.php b/library/think/Model.php
index a7547429..83aad670 100644
--- a/library/think/Model.php
+++ b/library/think/Model.php
@@ -834,7 +834,7 @@ abstract class Model implements \JsonSerializable, \ArrayAccess
         $model = get_called_class();
         $class = new static;
         if (!isset(self::$links[$model])) {
-            self::$links[$model] = Db::connect($class->connection);
+            self::$links[$model] = Db::connect($class->connection, $model);
         }
         // 设置当前数据表和模型名
         if (!empty($class->table)) {
diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index c7ae209e..6c7e4973 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -39,7 +39,7 @@ class Query
      */
     public function __construct($connection = '')
     {
-        $this->connection = $connection ?: Db::connect();
+        $this->connection = $connection ?: Db::connect([], true);
         $this->driver     = $this->connection->getDriverName();
     }
 
@@ -988,7 +988,7 @@ class Query
 
         $i            = 0;
         $currentModel = $this->options['model'];
-        $class        = new $this->options['model'];
+        $class        = new $currentModel;
         foreach ($with as $key => $relation) {
             $closure = false;
             if ($relation instanceof \Closure) {
@@ -1005,15 +1005,15 @@ class Query
             $info  = $class->getRelationInfo();
             if (in_array($info['type'], [Relation::HAS_ONE, Relation::BELONGS_TO])) {
                 if (0 == $i) {
-                    $joinName  = Loader::parseName(basename(str_replace('\\', '/', $this->options['model'])));
-                    $joinTable = $this->getTable();
-                    $this->table($joinTable)->alias($joinName)->field(true, false, $joinTable, $joinName);
+                    $name  = Loader::parseName(basename(str_replace('\\', '/', $currentModel)));
+                    $table = $this->getTable();
+                    $this->table($table)->alias($name)->field(true, false, $table, $name);
                 }
                 // 预载入封装
-                $table = $info['model']::getTable();
-                $name  = Loader::parseName(basename(str_replace('\\', '/', $info['model'])));
-                $this->via($name);
-                $this->join($table . ' ' . $name, $joinName . '.' . $info['localKey'] . '=' . $name . '.' . $info['foreignKey'])->field(true, false, $table, $name, $name . '__');
+                $joinTable = $model->getTable();
+                $joinName  = Loader::parseName(basename(str_replace('\\', '/', $info['model'])));
+                $this->via($joinName);
+                $this->join($joinTable . ' ' . $joinName, $name . '.' . $info['localKey'] . '=' . $joinName . '.' . $info['foreignKey'])->field(true, false, $joinTable, $joinName, $joinName . '__');
                 if ($closure) {
                     // 执行闭包查询
                     call_user_func_array($closure, [ & $this]);
@@ -1024,7 +1024,6 @@ class Query
             }
         }
         $this->via();
-        $this->model($currentModel);
         $this->options['with'] = $with;
         return $this;
     }