给用户控件ucQRCode增加属性:

​​//二维码图片
private PictureBox _pictureBoxFSHLQrCode;
public PictureBox PictureBoxFSHLQrCode
{​​
​​ get { return _pictureBoxFSHLQrCode; }
set { this.pictureBoxFSHLQrCode = value; }
}​​

在Form1窗体直接调用即可:

ucQRCode uQRCode=new ucQRCode();
ucQRCode.PictureBoxFSHLQrCode.属性= 要复制或传给用户控件上的控件的值;