其实看源码之后我就知道怎么设置了，没必要像你哪样啊。

前提是必须安装这个插件：　具体看readme
php composer.phar require "2amigos/yii2-date-picker-widget":"*"

    use dosamigos\datepicker\DatePicker;
    <?= $form->field($model, 'start_time')->widget(
        DatePicker::className(), [
        // inline too, not bad
        'inline' => true,
        'language' => 'zh-CN' , //--设置为中文
        'clientOptions' => [
            'autoclose' => false,
            'format' => 'yyyy-mm-dd'
        ]
    ]);?>