C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            treeView1.AllowDrop = true;
            treeView1.ItemDrag += new ItemDragEventHandler(treeView1_ItemDrag);
            treeView1.DragEnter += new DragEventHandler(treeView1_DragEnter);
            treeView1.DragDrop += new DragEventHandler(treeView1_DragDrop);
        }
            


        void treeView1_DragDrop(object sender, DragEventArgs e)
        {
         TreeNode moveNode = (TreeNode)e.Data.GetData("System.Windows.Forms.TreeNode");
         //根据鼠标坐标确定要移动到的目标节点
         Point pt;
         TreeNode targeNode;
         pt = ((TreeView)(sender)).PointToClient(new Point(e.X, e.Y));
         targeNode = this.treeView1.GetNodeAt(pt);
         //如果目标节点无子节点则添加为同级节点,反之添加到下级节点的未端
         TreeNode NewMoveNode = (TreeNode)moveNode.Clone();
         if (targeNode.Nodes.Count == 0)
         {
             targeNode.Parent.Nodes.Insert(targeNode.Index, NewMoveNode);
         }
         else
         {
             targeNode.Nodes.Insert(targeNode.Nodes.Count, NewMoveNode);
         }
         //更新当前拖动的节点选择
         treeView1.SelectedNode = NewMoveNode;
         //展开目标节点,便于显示拖放效果
         targeNode.Expand();
         //移除拖放的节点
         moveNode.Remove();
        }
        void treeView1_DragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent("System.Windows.Forms.TreeNode"))
            {
                e.Effect = DragDropEffects.Move;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }
        void treeView1_ItemDrag(object sender, ItemDragEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                DoDragDrop(e.Item, DragDropEffects.Move);
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            treeView1.LabelEdit = true;//可编辑状态。

            //添加一个节点，这个结点是根节点。
            TreeNode node = new TreeNode();
            node.Text = "hope";
            treeView1.Nodes.Add(node);
            TreeNode node1 = new TreeNode();
            node1.Text = "hopeone";
            TreeNode node11 = new TreeNode();
            node11.Text = "hopeoneone";
            TreeNode node2 = new TreeNode();
            node2.Text = "hopetwo";
            node1.Nodes.Add(node11);//在node1下面在添加一个结点。
            node.Nodes.Add(node1);//node下的两个子节点。
            node.Nodes.Add(node2);



            TreeNode t = new TreeNode("basil");//作为根节点。
            treeView1.Nodes.Add(t);
            TreeNode t1 = new TreeNode("basilone");
            t.Nodes.Add(t1);
            TreeNode t2 = new TreeNode("basiltwo");
            t.Nodes.Add(t2);
        }
    }
}