实现效果:

知识运用:
按钮的Width Height与Location属性
实现代码:
private void button1_MouseEnter(object sender, EventArgs e)
{
button1.Width =120;
button1.Height = 75;
button1.Font = new Font("楷体",17);
button1.Location = new Point((Width-button1.Width)/2,(Height-button1.Height)/2);
}