Use Load method in XmlDocument to load xml document : XmlDocument : XML C# Source Code

    
 

//Order.xml
/*
<?xml version="1.0" ?>
<ord:order xmlns:ord="http://mycompany/OrderML"
  xmlns:cli="http://mycompany/ClientML">

    <cli:client>
        <cli:firstName>Sally</cli:firstName>
        <cli:lastName>Sergeyeva</cli:lastName>
    </cli:client>

    <ord:orderItem itemNumber="3211"/>
    <ord:orderItem itemNumber="1155"/>

</ord:order>
*/
using System;
using System.Xml;

class MainClass {
    public static void Main() {
        XmlDocument doc = new XmlDocument();
        doc.Load("Order.xml");

        XmlNodeList matches = doc.GetElementsByTagName("*", "http://mycompany/OrderML");

        foreach (XmlNode node in matches) {
            Console.Write(node.Name + "\t");
            foreach (XmlAttribute attribute in node.Attributes) {
                Console.Write(attribute.Value + "  ");
            }
        }
    }
}