diff --git a/library/think/App.php b/library/think/App.php
index a1b1f287..8504bb35 100644
--- a/library/think/App.php
+++ b/library/think/App.php
@@ -74,7 +74,7 @@ class App
      * @return Response
      * @throws Exception
      */
-    public static function run(Request $request = null)
+    public static function run(?Request $request = null)
     {
         $request = is_null($request) ? Request::instance() : $request;
 
diff --git a/library/think/console/Command.php b/library/think/console/Command.php
index d0caad2f..0f8bfd0d 100644
--- a/library/think/console/Command.php
+++ b/library/think/console/Command.php
@@ -72,7 +72,7 @@ class Command
      * 设置控制台
      * @param Console $console
      */
-    public function setConsole(Console $console = null)
+    public function setConsole(?Console $console = null)
     {
         $this->console = $console;
     }
diff --git a/library/think/console/output/formatter/Stack.php b/library/think/console/output/formatter/Stack.php
index 4864a3f2..214ea3ae 100644
--- a/library/think/console/output/formatter/Stack.php
+++ b/library/think/console/output/formatter/Stack.php
@@ -28,7 +28,7 @@ class Stack
      * 构造方法
      * @param Style|null $emptyStyle
      */
-    public function __construct(Style $emptyStyle = null)
+    public function __construct(?Style $emptyStyle = null)
     {
         $this->emptyStyle = $emptyStyle ?: new Style();
         $this->reset();
@@ -57,7 +57,7 @@ class Stack
      * @return Style
      * @throws \InvalidArgumentException
      */
-    public function pop(Style $style = null)
+    public function pop(?Style $style = null)
     {
         if (empty($this->styles)) {
             return $this->emptyStyle;
diff --git a/library/think/db/Connection.php b/library/think/db/Connection.php
index 578cc8f9..1e132d56 100644
--- a/library/think/db/Connection.php
+++ b/library/think/db/Connection.php
@@ -406,7 +406,7 @@ abstract class Connection
      * @throws PDOException
      * @throws \Exception
      */
-    public function execute($sql, $bind = [], Query $query = null)
+    public function execute($sql, $bind = [], ?Query $query = null)
     {
         $this->initConnect(true);
         if (!$this->linkID) {
@@ -738,7 +738,7 @@ abstract class Connection
      * @param array $sqlArray SQL批处理指令
      * @return boolean
      */
-    public function batchQuery($sqlArray = [], $bind = [], Query $query = null)
+    public function batchQuery($sqlArray = [], $bind = [], ?Query $query = null)
     {
         if (!is_array($sqlArray)) {
             return false;
diff --git a/library/think/db/Query.php b/library/think/db/Query.php
index 4aa74eba..89fc0289 100644
--- a/library/think/db/Query.php
+++ b/library/think/db/Query.php
@@ -62,7 +62,7 @@ class Query
      * @param Connection $connection 数据库对象实例
      * @param Model      $model      模型对象
      */
-    public function __construct(Connection $connection = null, $model = null)
+    public function __construct(?Connection $connection = null, $model = null)
     {
         $this->connection = $connection ?: Db::connect([], true);
         $this->prefix     = $this->connection->getConfig('prefix');