设置窗体属性showinTask=false;加notifyicon控件notifyIcon1，为控件notifyIcon1的属性Icon添加一个icon图标;添加窗体最小化事件

// this.SizeChanged += new System.EventHandler(this.Form1_SizeChanged);
//上面一行是主窗体InitializeComponent()方法中需要添加的引用
private void Form1_SizeChanged(object sender, EventArgs e)
{
if (this.WindowState==FormWindowState.Minimized)
{
this.Hide();
this.notifyIcon1.Visible=true;
}
}
.添加点击图标事件(首先需要添加事件引用)：
private void notifyIcon1_Click(object sender, EventArgs e)
{
this.Visible = true;
this.WindowState = FormWindowState.Normal;
this.notifyIcon1.Visible = false;
}
 

.可以给notifyIcon添加右键菜单： 
主窗体中拖入一个ContextMenu控件contextMenu1，点中控件，在上下文菜单中添加菜单，notifyIcon1的ContextMenu行为中选中contextMenu1作为上下文菜单。 
(可以在子菜单中添加行为)