layui.use(['jquery','form', 'layer','upload'], function () {
    var form = layui.form(), layer = layui.layer, upload = layui.upload;
    var $ = layui.jquery;//重点处
    upload({
        elem: '#file',
        url: "admin/user/upload",
        title: '用户名单',
        ext: 'xls|xlsx', //那么，就只会支持这三种格式的上传。注意是用|分割。
        before: function(obj){
            layer.load(); //上传loading

            $('#file').after( '<input type="hidden" name="role_id" value="'+$('#id').val()+'" />' );
        },
        success: function (res, input) {
            layer.msg(res.message,{ time:1800},function(){
              
            });


        }
    });
})

这里关键是 $(‘#file’).after( ‘<input type=”hidden” name=”role_id” value=”‘+$(‘#id’).val()+'” />’ );

$(‘#file’) 对应upload的elem参数