先引入先在你的页面引入 bootstrap-select.css 和 bootstrap-select.js

<link href="~/Content/plugins/bootstrap-select/bootstrap-select.min.css" rel="stylesheet" />

<script src="~/Content/plugins/bootstrap-select/bootstrap-select.min.js"></script>

 <select class="selectpicker form-control" data-none-selected-text="全部" multiple data-actions-box="true" data-live-search="true">

 </select>

只要在<select>控件里加入
multiple:多选

data-actions-box="true"：全选，全不选

data-live-search="true"：查询

data-none-selected-text="全部"：未选中时显示

data-max-options="20"：最多可选条数

selectpicker：自定义的class名用于 selectpicker配置

$(".selectpicker").selectpicker("refresh");