XmlDictionaryReader reader = JsonReaderWriterFactory.CreateJsonReader(Encoding.UTF8.GetBytes(sJson), XmlDictionaryReaderQuotas.Max);
XmlDocument doc = new XmlDocument();
doc.Load(reader);

收藏一下吧 以后万一用的到

我试了一下，json字符串需要把键加"才行
如：{Name:"aaa",Value:1}  这里Name和Value是键这样写法转换的时候报错
需要写成
{"Name":"aaa","Value":1}

这个是第二种方法，这个键加不加"都正常翻译

  /// <summary>
        /// json字符串转换为Xml对象
        /// </summary>
        /// <param name="sJson"></param>
        /// <returns></returns>
        public static XmlDocument Json2Xml(string sJson)
        {
            //XmlDictionaryReader reader = JsonReaderWriterFactory.CreateJsonReader(Encoding.UTF8.GetBytes(sJson), XmlDictionaryReaderQuotas.Max);
            //XmlDocument doc = new XmlDocument();
            //doc.Load(reader);

            JavaScriptSerializer oSerializer = new JavaScriptSerializer();
            Dictionary<string, object> Dic = (Dictionary<string, object>)oSerializer.DeserializeObject(sJson);
            XmlDocument doc = new XmlDocument();
            XmlDeclaration xmlDec;
            xmlDec = doc.CreateXmlDeclaration("1.0", "gb2312", "yes");
            doc.InsertBefore(xmlDec, doc.DocumentElement);
            XmlElement nRoot = doc.CreateElement("root");
            doc.AppendChild(nRoot);
            foreach (KeyValuePair<string, object> item in Dic)
            {
                XmlElement element = doc.CreateElement(item.Key);
                KeyValue2Xml(element, item);
                nRoot.AppendChild(element);
            }
            return doc;
        }

        private static void KeyValue2Xml(XmlElement node, KeyValuePair<string, object> Source)
        {
            object kValue = Source.Value;
            if (kValue.GetType() == typeof(Dictionary<string, object>))
            {
                foreach (KeyValuePair<string, object> item in kValue as Dictionary<string, object>)
                {
                    XmlElement element = node.OwnerDocument.CreateElement(item.Key);
                    KeyValue2Xml(element, item);
                    node.AppendChild(element);
                }
            }
            else if (kValue.GetType() == typeof(object[]))
            {
                object[] o = kValue as object[];
                for (int i = 0; i < o.Length; i++)
                {
                    XmlElement xitem = node.OwnerDocument.CreateElement("Item");
                    KeyValuePair<string, object> item = new KeyValuePair<string, object>("Item", o[i]);
                    KeyValue2Xml(xitem, item);
                    node.AppendChild(xitem);
                }
                  
            }
            else
            {
                XmlText text = node.OwnerDocument.CreateTextNode(kValue.ToString());
                node.AppendChild(text);
            }
        }