$pdf = new Pdf([

    'mode' => Pdf::MODE_UTF8,

    'format' => Pdf::FORMAT_A4,

    'orientation' => Pdf::ORIENT_LANDSCAPE,

    'destination' => Pdf::DEST_BROWSER,    //值为Pdf::DEST_FILE时生成文件

    'cssFile' => '@vendor/kartik-v/yii2-mpdf/assets/kv-mpdf-bootstrap.min.css',
　　//设置中文

    'options' => [

        'title' => '中文',

        'autoLangToFont' => true,

        'autoScriptToLang' => true,

        'autoVietnamese' => true,

        'autoArabic' => true,

    ],

]);

$pdf->content=$contents;

$pdf->render();