A light guide plate includes a plate-like body, a surface thereof being a light-emitting surface, and a projection extending from a surface of the body away from the light-emitting surface along a direction opposite to the light-emitting surface. The projection separates the body of the light guide plate from the reflecting sheet, so that an air layer is formed between the light guide plate and the reflecting sheet, thus rendering the body of the light guide plate and the reflecting sheet hardly attachable to each other. A backlight module comprises said light guide plate.