前台：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="TreeView._Default" %>

后台：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace TreeView
{
    public partial class _Default : System.Web.UI.Page
    {
        public static string st = ConfigurationManager.ConnectionStrings["sql"].ToString();
        private DataTable dts=new DataTable();
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                dts = CreateTable();
                CreateNode();
            }
        }
        public void CreateNode()
        {
            DataRow[] dr = dts.Select("ParentID=0");
            if(dr.Length>0)
            {
                foreach(DataRow drr in dr)
                {
                    TreeNode tn = new TreeNode();
                    tn.Value = drr["MenuID"].ToString();
                    tn.Text = drr["MenuName"].ToString();
                    tn.Expanded = false;
                    tn.SelectAction = TreeNodeSelectAction.Expand;
                    TreeView1.Nodes.Add(tn);
                    CreateChild(tn,dts);
                }
            }
            else
            {
                TreeNode t=new TreeNode();
                t.Value="空";
                t.Text="空";
                t.Expanded=false;
                t.SelectAction=TreeNodeSelectAction.Expand;
                TreeView1.Nodes.Add(t);
            }
        }
        public void CreateChild(TreeNode tnn, DataTable dtt)
        {
            DataRow[] dr = dtt.Select("ParentID=" + tnn.Value);
            if (dr.Length > 0)
            {
                foreach (DataRow drw in dr)
                {
                    TreeNode ts = new TreeNode();
                    ts.Value = drw["MenuID"].ToString();
                    ts.Text = drw["MenuName"].ToString();
                    ts.SelectAction = TreeNodeSelectAction.Expand;
                    ts.Expanded = false;
                    tnn.ChildNodes.Add(ts);
                    CreateChild(ts, dtt);
                }
            }
        }
        public DataTable CreateTable()
        {
            DataTable d = new DataTable();
            using(SqlConnection sql=new SqlConnection(st))
            {

                SqlCommand sq=new SqlCommand("select * from TreeViewName",sql);
                SqlDataAdapter sda=new SqlDataAdapter();
                sda.SelectCommand = sq;
                sda.Fill(d);

            }
            return d;
        }
    }
}