在formload事件中加入以下代码:
System.Windows.Forms.Button myButton = new System.Windows.Forms.Button();
myButton.BackColor = Color.Blue; //Lets change the color
myButton.Size = new Size(100, 100);
System.Drawing.Drawing2D.GraphicsPath myGraphicsPath = new System.Drawing.Drawing2D.GraphicsPath(); //The GraphicsPath class allows us to define custom paths
myGraphicsPath.AddEllipse(5, 5, 90, 90); //A big circle
myButton.Region = new Region(myGraphicsPath); //Associating the path made by us to the button's region
this.Controls.Add(myButton);