<select class="selectpicker" multiple>      
</select>

<script type="text/javascript">
      getOption();
      function getOption(){
        $.ajax({
          type:"get",
          url:"test.json",
          async:true,
          success:function (data) {
            var str = "";
            for(var i = 0;i<data.length;i++){
              str+='<option>'+data[i].value+'</option>'
            }
            $(".selectpicker").html(str);
            
            $(".selectpicker" ).selectpicker('refresh');
          }
        });
      }
</script>