首先添加引用

using Newtonsoft.Json;

示例代码

dynamic orderJson = new JObject();
//简单用法
 orderJson.state = "201";
 orderJson.msg = "未找到订单！";
 return orderJson.ToString();
//添加子集合
 orderJson.ticketlist = new JArray() as dynamic;
 dynamic ticketJson = new JObject();
 ticketJson.state = "审核中";
orderJson.ticketlist.Add(ticketJson);
 return orderJson.ToString();