<?xml version="1.0" encoding="utf-8" ?>
<root >
<BM >
<Name >COD排放</Name >
<Formel ></Formel >
<Explain ></Explain >
<BM >
<Name >排放公式一</Name >
<Formel >a+b</Formel >
<Explain >2</Explain >
</BM >
<BM >
<Name >排放公式二</Name >
<Formel >a+b-c</Formel >
<Explain >2</Explain >
</BM >
</BM >
<BM >
<Name >SO2排放</Name >
<Formel >a*(b+c)</Formel >
<Explain ></Explain >
<BM >
<Name >计算公式一</Name >
<Formel >a*(b+c)-d</Formel >
<Explain >2</Explain >
</BM >
<BM >
<Name >计算公式二</Name >
<Formel >a*(b-c)+d</Formel >
<Explain >2</Explain >
<BM >
<Name >计算公式三</Name >
<Formel >a-b</Formel >
<Explain >2</Explain >
<BM >
<Name >计算公式四</Name >
<Formel >a+b*c</Formel >
<Explain >2</Explain >
</BM >
</BM >
</BM >
</BM >
</root >



C# code 

private void populateTreeview()
{
OpenFileDialog dlg = new OpenFileDialog();
dlg.Title = "Open XML Document";
dlg.Filter = "XML Files (*.xml)|*.xml";
dlg.FileName = Application.StartupPath + "\\..\\..\\example.xml";
if (dlg.ShowDialog() == DialogResult.OK)
{
try
{
//Just a good practice -- change the cursor to a
//wait cursor while the nodes populate
            this.Cursor = Cursors.WaitCursor;
//First, we'll load the Xml document
            XmlDocument xDoc = new XmlDocument();
xDoc.Load(dlg.FileName);
//Now, clear out the treeview,
//and add the first (root) node
            treeView1.Nodes.Clear();
treeView1.Nodes.Add(new
TreeNode(xDoc.DocumentElement.Name));
TreeNode tNode = new TreeNode();
tNode = (TreeNode)treeView1.Nodes[0];
//We make a call to addTreeNode,
//where we'll add all of our nodes
            addTreeNode(xDoc.DocumentElement, tNode);
//Expand the treeview to show all nodes
            treeView1.ExpandAll();
}
catch(XmlException xExc)
//Exception is thrown is there is an error in the Xml
        {
MessageBox.Show(xExc.Message);
}
catch(Exception ex) //General exception
        {
MessageBox.Show(ex.Message);
}
finally
{
this.Cursor = Cursors.Default; //Change the cursor back
        }
}
}
//This function is called recursively until all nodes are loaded
private void addTreeNode(XmlNode xmlNode, TreeNode treeNode)
{
XmlNode xNode;
TreeNode tNode;
XmlNodeList xNodeList;
if (xmlNode.HasChildNodes) //The current node has children
    {
xNodeList = xmlNode.ChildNodes;
for(int x=0; x<=xNodeList.Count-1; x++)
//Loop through the child nodes
        {
xNode = xmlNode.ChildNodes[x];
treeNode.Nodes.Add(new TreeNode(xNode.Name));
tNode = treeNode.Nodes[x];
addTreeNode(xNode, tNode);
}
}
else //No children, so add the outer xml (trimming off whitespace)
        treeNode.Text = xmlNode.OuterXml.Trim();
}
save
private StreamWriter sr;
public void exportToXml(TreeView tv, string filename)
{
sr = new StreamWriter(filename, false, System.Text.Encoding.UTF8);
//Write the header
    sr.WriteLine("<?xml version=\"1.0\" encoding=\"utf-8\" ?>");
//Write our root node
    sr.WriteLine("<" + treeView1.Nodes[0].Text + ">");
foreach (TreeNode node in tv.Nodes)
{
saveNode(node.Nodes);
}
//Close the root node
    sr.WriteLine("</" + treeView1.Nodes[0].Text + ">");
sr.Close();
}
private void saveNode(TreeNodeCollection tnc)
{
foreach (TreeNode node in tnc)
{
//If we have child nodes, we'll write
//a parent node, then iterrate through
//the children
        if (node.Nodes.Count > 0)
{
sr.WriteLine("<" + node.Text + ">");
saveNode(node.Nodes);
sr.WriteLine("</" + node.Text + ">");
}
else //No child nodes, so we just write the text
            sr.WriteLine(node.Text);
}
}







修该的话就不用写了吧 

直接删除treenode就可以了 

在treenode的选中事件里做