新增引用：

using Newtonsoft.Json.Linq;
using System.Collections.Generic;

操作json字串方法

    /// <summary>
    /// linq操作json
    /// </summary>
    public void OpearteJson()
    {
        string jsonStr = "{\"name\":\"小明\",\"age\":\"20\",\"phone\":[{\"type\":\"phone\"},{\"type\":\"huawei\"}]}";
        
 
var jsonObject = JObject.Parse(jsonStr);
        var name = jsonObject["name"].ToString();//根據物件key獲取value
        var phoneArr = jsonObject["phone"] as JArray;//獲取陣列key鍵的值
        foreach (JObject item in phoneArr)//遍歷json物件陣列
        {
            foreach (var keyValue in item)//迴圈遍歷json物件鍵值對
            {
                
 
var key = keyValue.Key;
                var value = keyValue.Value.ToString();
            }
        }
    }

遍歷json字串的key value值:

/// <summary>
    /// 獲取json字串的鍵值對,不包含陣列json
    /// </summary>
    /// <param name="jsonStr">json字串,例如:"{\"name\":\"szl\",\"age\":\"20\"}"</param>
    /// <returns></returns>
 

    public Dictionary<string, List<string>> GetJsonKeyValue(string jsonStr)
    {
        JObject jsonObj = JObject.Parse(jsonStr);//將json字串轉換成json物件
        Dictionary<string, List<string>> result = new Dictionary<string, List<string>>();
        List<string> key = new List<string>();
        List<string> value = new List<string>();
        foreach (var item in jsonObj)//遍歷json物件的所有鍵值對
        {
            key.Add(item.Key);
            value.Add(item.Value.ToString());
        }
        result.Add("key", key);
        result.Add("value", value);
        return result;
    }