این هم جواب سوال خودم
orgPanel1.Dock = DockStyle.None; // If Panel Dockstyle is in Fill mode
orgPanel1.Width = orgPanel1.PreferredSize.Width+15; // Original Size without scrollbar
orgPanel1.Height = orgPanel1.PreferredSize.Height+15; // Original Size without scrollbar
Bitmap bmp2 = new Bitmap(orgPanel1.Width, orgPanel1.Height);
orgPanel1.DrawToBitmap(bmp2, new Rectangle(0, 0, orgPanel1.Width, orgPanel1.Height));
bmp2.Save("C:\\panel.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
orgPanel1.Dock = DockStyle.Fill;