A light guide plate and a backlight module are provided. The backlight module includes a light source and the light guide plate. The light source includes a light emitting surface. The light guide plate includes a light incident surface, a first surface, and a second surface, wherein the first surface is opposite to the second surface. The light guide plate is disposed at a side of the light source. The light incident surface of the light guide plate is opposite to the light emitting surface of the light source. The light incident surface is connected to the first surface and the second surface and includes a first curved surface and a second curved surface. The first curved surface is adjacent to the first surface, and the second curved surface is adjacent to the second surface. The first curved surface is a concave surface.