实现效果：

代码：

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 NoBorderForm{ public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { } Point mouseOff;//鼠标移动位置变量 bool leftFlag;//标记是否为左键 private void Form1_MouseDown(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { mouseOff = new Point(-e.X, -e.Y); //得到变量的值 leftFlag = true; //点击左键按下时标注为true; } } private void Form1_MouseMove(object sender, MouseEventArgs e) { if (leftFlag) { Point mouseSet = Control.MousePosition; mouseSet.Offset(mouseOff.X, mouseOff.Y); //设置移动后的位置 Location = mouseSet; } } private void Form1_MouseUp(object sender, MouseEventArgs e) { if (leftFlag) { leftFlag = false;//释放鼠标后标注为false; } } private void button1_Click(object sender, EventArgs e) { DialogResult dr = MessageBox.Show("yes/no", "exit", MessageBoxButtons.YesNo, MessageBoxIcon.Warning); if (dr == DialogResult.Yes) { this.Close(); } else { return; } } private void button2_Click(object sender, EventArgs e) { this.WindowState = FormWindowState.Minimized; } private void checkBox1_CheckedChanged(object sender, EventArgs e) { } private void Form1_Click(object sender, EventArgs e) { } private void panel1_Click(object sender, EventArgs e) { } private void textBox1_Click(object sender, EventArgs e) { } private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e) { System.Diagnostics.Process.Start("http://"); } private void button4_Click(object sender, EventArgs e) { } }}