XmlDocument xml = new XmlDocument();

XmlDeclaration dec = xml.CreateXmlDeclaration("1.0", null, null);

xml.AppendChild(dec);

XmlComment com = xml.CreateComment("这是注释");

xml.AppendChild(com);

XmlElement root = xml.CreateElement("symbol");

root.InnerText = "root";

xml.AppendChild(root);

XmlElement symbol = xml.CreateElement("symbol");

symbol.InnerText = "InnerText";

symbol.SetAttribute("ATT", "Attribute");

symbol.SetAttribute("ATT2", "Attribute2");

xml.DocumentElement.AppendChild(symbol);

XmlTextWriter xw = new XmlTextWriter("d:\\test.xml", null);

xw.Formatting = Formatting.Indented;

xml.WriteContentTo(xw);

xw.Close();