A projection display device is disclosed herein. The projection display device includes an image processing module and a light source driver. The image processing module is configured for receiving an image data and generating a display signal which includes an image period and a black state period. The light source driver is configured for generating a light driving signal to drive a projection light source, wherein the light driving signal includes a first segment and a second segment in the black state period, and the average amplitude of the light driving signal in the second segment is lower than the average amplitude of the light driving signal in the image period. A driving method is disclosed herein as well.