diff --git a/README.md b/README.md
index 79da5fd..82fe5e8 100644
--- a/README.md
+++ b/README.md
@@ -22,9 +22,9 @@
 - [x] 支持同步历史附件到阿里云对象存储 OSS
 - [x] 支持阿里云 OSS 图片处理
 - [x] 支持上传文件自动重命名
-- [x] 支持使用 RAM 操作
+- [x] 支持使用 ECS 的 RAM 操作
 - [x] 支持原图保护
-- [x] 支持 `wp-cli` 命令上传文件
+- [x] 支持 `wp-cli` 命令上传/删除文件
 
 ## 安装
 
diff --git a/aliyun-oss-wordpress.php b/aliyun-oss-wordpress.php
index 45892f5..9f729e8 100644
--- a/aliyun-oss-wordpress.php
+++ b/aliyun-oss-wordpress.php
@@ -3,7 +3,7 @@
 Plugin Name: OSS Aliyun
 Plugin URI: https://github.com/sy-records/aliyun-oss-wordpress
 Description: 使用阿里云对象存储 OSS 作为附件存储空间。（This is a plugin that uses Aliyun Object Storage Service for attachments remote saving.）
-Version: 1.4.14
+Version: 1.4.15
 Author: 沈唁
 Author URI: https://qq52o.me
 License: Apache2.0
@@ -19,7 +19,7 @@ use OSS\Credentials\CredentialsProvider;
 use AlibabaCloud\Credentials\Credential;
 use OSS\Credentials\StaticCredentialsProvider;
 
-define('OSS_VERSION', '1.4.14');
+define('OSS_VERSION', '1.4.15');
 define('OSS_BASEFOLDER', plugin_basename(dirname(__FILE__)));
 
 if (!function_exists('get_home_path')) {
@@ -75,33 +75,36 @@ function oss_set_options()
 
 function oss_get_client()
 {
-    $oss_opt = get_option('oss_options', true);
-    $roleName = esc_attr($oss_opt['role_name'] ?? '');
-    $endpoint = oss_get_bucket_endpoint($oss_opt);
+    $oss_options = get_option('oss_options', true);
+    $role_name = esc_attr($oss_options['role_name'] ?? '');
+    $endpoint = oss_get_bucket_endpoint($oss_options);
+    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? 'https://' : 'http://';
 
-    if (!empty($roleName)) {
+    if (!empty($role_name)) {
         $ecsRamRole = new Credential([
             // 填写Credential类型，固定值为ecs_ram_role。
             'type' => 'ecs_ram_role',
             // 填写角色名称。
-            'role_name' => $roleName,
+            'role_name' => $role_name,
         ]);
         $providerWrapper = new OSSCredentialsWrapper($ecsRamRole);
         $provider = $providerWrapper->getCredentials();
-        $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? 'https://' : 'http://';
-        $config = ['provider' => $provider, 'endpoint'=> $protocol . $endpoint];
-        return new OssClient($config);
+    } else {
+        $provider = new StaticCredentialsProvider(esc_attr($oss_options['accessKeyId']), esc_attr($oss_options['accessKeySecret']));
     }
-
-    $accessKeyId = esc_attr($oss_opt['accessKeyId']);
-    $accessKeySecret = esc_attr($oss_opt['accessKeySecret']);
-    return new OssClient($accessKeyId, $accessKeySecret, $endpoint);
+    $config = [
+        'provider'         => $provider,
+        'endpoint'         => $protocol . $endpoint,
+        'signatureVersion' => OssClient::OSS_SIGNATURE_VERSION_V4,
+        'region'           => str_replace('oss-', '', esc_attr($oss_options['regional'])),
+    ];
+    return new OssClient($config);
 }
 
-function oss_get_bucket_endpoint($oss_option)
+function oss_get_bucket_endpoint($oss_options)
 {
-    $oss_regional = esc_attr($oss_option['regional']);
-    if ($oss_option['is_internal'] == 'true') {
+    $oss_regional = esc_attr($oss_options['regional']);
+    if ($oss_options['is_internal'] == 'true') {
         return "{$oss_regional}-internal.aliyuncs.com";
     }
 
@@ -110,8 +113,8 @@ function oss_get_bucket_endpoint($oss_option)
 
 function oss_get_bucket_name()
 {
-    $oss_opt = get_option('oss_options', true);
-    return $oss_opt['bucket'];
+    $oss_options = get_option('oss_options', true);
+    return $oss_options['bucket'];
 }
 
 /**
@@ -573,6 +576,11 @@ function oss_setting_post_thumbnail_style($html, $post_id, $post_image_id)
     return $html;
 }
 
+/**
+ * @link https://help.aliyun.com/zh/oss/user-guide/regions-and-endpoints
+ * @param string $regional
+ * @return void
+ */
 function oss_get_regional($regional)
 {
     $options = [
diff --git a/oss-commands.php b/oss-commands.php
index 87d4162..4c5eb90 100644
--- a/oss-commands.php
+++ b/oss-commands.php
@@ -6,7 +6,6 @@ if (!class_exists('WP_CLI')) {
 
 class OSS_CLI_Commands
 {
-
     /**
      * 同步文件夹到 OSS
      *
diff --git a/readme.txt b/readme.txt
index 4ca23a4..a898331 100644
--- a/readme.txt
+++ b/readme.txt
@@ -5,7 +5,7 @@ Tags: oss, 阿里云, 对象存储, aliyun
 Requires at least: 4.6
 Tested up to: 6.6
 Requires PHP: 7.1
-Stable tag: 1.4.14
+Stable tag: 1.4.15
 License: Apache2.0
 License URI: http://www.apache.org/licenses/LICENSE-2.0.html
 
@@ -27,9 +27,9 @@ License URI: http://www.apache.org/licenses/LICENSE-2.0.html
 6. 支持同步历史附件到阿里云对象存储 OSS
 7. 支持阿里云 OSS 图片处理
 8. 支持上传文件自动重命名
-9. 支持使用 RAM 操作
+9. 支持使用 ECS 的 RAM 操作
 10. 支持原图保护
-11. 支持 `wp-cli` 命令上传文件
+11. 支持 `wp-cli` 命令上传/删除文件
 12. 插件更多详细介绍和安装：[https://github.com/sy-records/aliyun-oss-wordpress](https://github.com/sy-records/aliyun-oss-wordpress)
 
 ## 其他插件
@@ -76,6 +76,10 @@ License URI: http://www.apache.org/licenses/LICENSE-2.0.html
 
 == Changelog ==
 
+= 1.4.15 =
+
+- 将阿里云V1签名升级为V4签名
+
 = 1.4.14 =
 
 - 支持 `wp-cli` 命令删除文件