You can sort using LINQ to Xml, if XmlDocument is not the case
XDocument input = XDocument.Load(@"input.xml");
XDocument output = new XDocument(
new XElement("Users",
from node in input.Root.Elements()
orderby node.Attribute("Name").Value descending
select node));
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…