//鼠标光标进入按钮并创建按钮
 private void btn_Start_MouseEnter(object sender, EventArgs e)
        {
            Point p =new Point(MousePosition.X+50,MousePosition.Y+50);
            Point P_bf = PointToClient(p);
           
            Button btn_float=new Button();
            btn_float.Location = P_bf;
           btn_float.Size=new Size(150,50);
           btn_float.Name = "123";
            btn_float.Text = "魂叹啊";
            this.Controls.Add(btn_float);
        }
问题来了鼠标离开事件不知如何获取上面创建的新按钮
  private void btn_Start_MouseLeave(object sender, EventArgs e)
        {
             this.Controls.Remove(xxoo);
             //求高人指点xxoo --！   
        }

Button btn_float ;
先声明Button的全局变量，然后在MouseEnter事件里new。