代码如下，添加到当前主题的 functions.php 文件即可：

function translate_chinese_post_title_to_en_for_slug( $title ) {
    /*
    transtype：
    trans
    realtime
     */
    $translation_render = 'http://fanyi.baidu.com/v2transapi?from=zh&to=en&transtype=realtime&simple_means_flag=3&query='.$title;
    $wp_http_get = wp_safe_remote_get( $translation_render );
    if ( empty( $wp_http_get->errors ) ) { 
        if ( ! empty( $wp_http_get['body'] ) ) {
            $trans_result = json_decode( $wp_http_get['body'], true );
            $trans_title = $trans_result['trans_result']['data'][0]['dst'];
            return $trans_title;
        }
    }
    return $title;
} 
add_filter( 'sanitize_title', 'translate_chinese_post_title_to_en_for_slug', 1 );