1.在form中添加一个NotifyIcon控件。　　　

2.把87.ico这个图标放在binDebug目录下。

3.

        //窗体最小化的时候所发生的事件
        private void Form1_SizeChanged(object sender, EventArgs e)
        {
            if (this.WindowState == FormWindowState.Minimized)
            {
                this.ShowInTaskbar = false;
                this.notifyIcon1.Visible = true;
            }
        }

        //单击任务栏的小图标时候发生的事件
        private void notifyIcon1_Click(object sender, EventArgs e)
        {
            if (this.WindowState == FormWindowState.Minimized)
            {
                this.WindowState = FormWindowState.Normal;
            }
            this.Activate();
            this.notifyIcon1.Visible = false;
            this.ShowInTaskbar = true;
        }