private void Form1_Load(object sender, EventArgs e) { frm=new Form2(); frm.TopLevel = false; frm.Show(); this.panel1.Controls.Add(frm); this.panel1.Resize+=new EventHandler(panel1_Resize); } Form2 frm; private void panel1_Resize(object sender, EventArgs e) { if (frm != null) { frm.Size = this.panel1.Size; } }https://bbs.csdn.net/topics/310148741