<script src="~/Assets/js/bootstrap-multiselect.min.js"></script>
  <link href="~/Assets/css/bootstrap-multiselect.css" rel="external nofollow" rel="stylesheet" />

 function RegSelect() {
      $('.multiselect').multiselect({
        buttonClass: 'btn btn-white ',
        enableFiltering: true,
        enableHTML: true,
        includeSelectAllOption: true,
        selectAllText: '全选',
        allSelectedText: '全部选中',
        nonSelectedText: '请选择',
        nSelectedText: '个被选中',
        templates: {
          button: '<button type="button" class="multiselect dropdown-toggle" data-toggle="dropdown"><span class="multiselect-selected-text"></span>  <b class="fa fa-caret-down"></b></button>',
          ul: '<ul class="multiselect-container dropdown-menu"></ul>',
          filter: '<li class="multiselect-item filter"><div class="input-group"><span class="input-group-addon"><i class="fa fa-search"></i></span><input class="form-control multiselect-search" type="text"></div></li>',
          filterClearBtn: '<span class="input-group-btn"><button class="btn btn-default btn-white btn-grey multiselect-clear-filter" type="button"><i class="fa fa-times-circle red2"></i></button></span>',
          li: '<li><a tabindex="0"><label></label></a></li>',
          divider: '<li class="multiselect-item divider"></li>',
          liGroup: '<li class="multiselect-item multiselect-group"><label></label></li>'
        }
      });
    }

 <div class="form-group">
          <label for="RepairOrg" class="col-sm-3 control-label">维修单位</label>
          <div class="col-sm-9">
            @Html.DropDownList("RepairOrgUID", ViewBag.OrgList as List<SelectListItem>, "请选择", new { @class = "form-control multiselect", onchange = "OrgChange(this)", id = "RepairOrg" })
          </div>
        </div>
        <div class="form-group">
          <label for="RepairContact" class="col-sm-3 control-label">维修人</label>
          <div class="col-sm-9">
            @Html.DropDownList("RepairContactUID", ViewBag.ContactList as List<SelectListItem>, "请选择", new { @class = "form-control multiselect", id = "RepairContact" })
          </div>
        </div>

function OrgChange(obj, patientID) {
      var RepairOrg = $(obj).val();
      $.post("/TerminalManage/GetContactByOrg", { RepairOrg: RepairOrg }, function (data) {     
        var newCitys = new Array();
        var obj = new Object();
        obj = {
          label: "请选择",
          value: ""
        };
        newCitys.push(obj);
        for (var i = 0; i < data.length; i++) {
          obj = {
            label: data[i].Text,
            value: data[i].Value
          };
          newCitys.push(obj);
        }
        $("#RepairContact").multiselect('dataprovider', newCitys);
        $('#RepairContact').multiselect('refresh');
      });
    }