你可以去看看一些基础知识，也就是方法自己调用自己，如下面的方法：

private void a()

{

　　a();

}

public void RecureTreeView(TreeNodeCollection nodes){

　　foreach(TreeNode node in nodes){

　　RecureTreeView(node.Nodes);

　　Debug.WriteLine(node.Text);

　　}

}

 递归就是自己调用自己，自己写一个方法体，在方法体里面再次调用自己就ok了。

 void dg1(string path,TreeNode tn)
        {
            string[] str = Directory.GetDirectories(path);
            foreach (string s in str)
            {
              TreeNode Tn=tn.Nodes.Add(Path.GetFileName(s));
              dg1(s, Tn);
            }

            string[] file = Directory.GetFiles(path);
            foreach (string s1 in file)
            {
                tn.Nodes.Add(Path.GetFileName(s1));
            }
        }

private void CreateChildNode(TreeNodeCollection nodes, DataTable dt, int parentId)
        {
            string selectId = string.Format("FatherId={0}", parentId);
            DataRow[] rowList = dt.Select(selectId);
            foreach (DataRow dr in rowList)
            {
                TreeNode tn = new TreeNode();
                nodes.Add(tn);
                tn.Text = dr["PowerName"].ToString();
                tn.Value = dr["Id"].ToString();
                tn.Expanded = false;
                //tn.ImageUrl = "~/SystemSet/Image/Root.gif";
                tn.NavigateUrl = dr["LinkUrl"].ToString();
                tn.Target = "I1";
                int id = int.Parse(tn.Value);
               // node.ChildNodes.Add(tn);
               
                CreateChildNode(tn.ChildNodes, dt, id);
                dt.Rows.Remove(dr);