https://www.cnblogs.com/hfzsjz/archive/2010/08/13/1799068.html

   void ArrangeButtons(Panel pn)
         {
            int x = 0, y = 0;
             System.Windows.Forms.Control.ControlCollection ct = pn.Controls;

            //for (int i = 0; i < ct.Count; i++)
            for (int i = ct.Count - 1; i >= 0
 
; i--)
             {
                 ct[i].Location = new System.Drawing.Point(x, y);
                 x = x + ct[i].Width + 5;
                if (x + ct[i].Width > pn.Width)
                 {
                     x = 0;
                     y = y + ct[i].Height + 5;
                 }
             }
         }

        
 
private void buttonArrangeButtons_Click(object sender, EventArgs e)
         {
             ArrangeButtons(panel1);
         }

   void ArrangeButtons(Panel pn)
         {
            int x = 0, y = 0;
             System.Windows.Forms.Control.ControlCollection ct = pn.Controls;

            
 
//for (int i = 0; i < ct.Count; i++)
            for (int i = ct.Count - 1; i >= 0; i--)
             {
                 ct[i].Location = new System.Drawing.Point(x, y);
                 x = x + ct[i].Width + 5;
                if (x + ct[i].Width > pn.Width)
                 {
                     x = 0;
                     y = y + ct[i].Height + 5;
                 }
             }
         }

        private void buttonArrangeButtons_Click(object sender, EventArgs e)
         {
             ArrangeButtons(panel1);
         }