private void XmlOperation_Load(object sender, EventArgs e)
        {
            path = AppDomain.CurrentDomain.BaseDirectory + @"NameList.xml";
            xml.Load(path);//加载xml文件
            bindTvXml();
        }

        /// <summary>
        /// 绑定TreeView
        /// </summary>
        private void bindTvXml()
        {
            for (int i = 0; i < xml.DocumentElement.ChildNodes.Count; i++)
            {
                XmlNode Xnode = xml.DocumentElement.ChildNodes[i];
                TreeNode node = new TreeNode();
                node.Text = Xnode.Attributes["name"].Value;
                node.Tag = Xnode;
                bindChildNode(node, Xnode);//绑定子节点
                TvXml.Nodes.Add(node);
                TvXml.HideSelection = false;
            }
        }
        
        /// <summary>
        /// 递归绑定子节点
        /// </summary>
        /// <param name="node"></param>
        /// <param name="xml"></param>
        private void bindChildNode(TreeNode node, XmlNode xml)
        {
            for (int i = 0; i < xml.ChildNodes.Count; i++)
            {
                TreeNode Childnode = new TreeNode();
                XmlNode ChildXml = xml.ChildNodes[i];
                Childnode.Text = ChildXml.Value;
                Childnode.Name = "1";
                Childnode.Tag = xml.ChildNodes[i];
                if (ChildXml.HasChildNodes)
                {
                    if (ChildXml.ChildNodes[0].NodeType == XmlNodeType.Text)
                        Childnode.Text = ChildXml.ChildNodes[0].InnerText;
                    else
                        bindChildNode(Childnode, ChildXml);
                }
                node.Nodes.Add(Childnode);
            }
           
        }

------解决方案--------------------
C# code
        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.Load(@"c:\test.xml");
        XmlNode node = xmlDoc.SelectSingleNode(@"//Placemark/Name[text()='sole']");
        node.ParentNode["LineString"]["coordinates"].InnerXml = "新值";
        xmlDoc.Save(@"c:\test.xml");