解决方法：
1
pictureBox1.Image = Image.FromStream(System.Net.WebRequest.Create(http://www.baidu/new.gif ).GetResponse().GetResponseStream());
2.
pictureBox1.Image = new Bitmap((new System.Net.WebClient()).OpenRead(http://www.baidu/new.gif ));原文：https://www.cnblogs.com/lt0000/p/8820588.html