Image img = this.pictureBox1.Image; img.RotateFlip(RotateFlipType.Rotate90FlipNone); this.pictureBox1.Image = img;
顺时针旋转90度 RotateFlipType.Rotate90FlipNone
逆时针旋转90度 RotateFlipType.Rotate270FlipNone
水平翻转 RotateFlipType.Rotate180FlipY
垂直翻转 RotateFlipType.Rotate180FlipX
原文：https://www.cnblogs.com/zyl1994/p/12566235.html