How to get Xml as string from XDocument?

Use ToString() to convert XDocument into a string:

string result = string.Empty;
XElement root = new XElement("xml",
    new XElement("MsgType", "<![CDATA[" + "text" + "]]>"),
    new XElement("Content", "<![CDATA[" + "Hi, this is Wilson Wu Testing for you! You can ask any question but no answer can be replied...." + "]]>"),
    new XElement("FuncFlag", 0)
);
result = root.ToString();