A backlight module includes a light guide plate, at least one light source, and a reflective plate. The light source is configured for emitting light toward the light guide plate. The reflective plate has a plurality of reflective units arranging along a curved direction. Each of the reflective units includes a body and a plurality of microstructures. The body has a main surface facing the light guide plate. The plurality of microstructures are disposed on the main surface of the body. Each of the microstructures has a reflective surface. A first angle is included between the reflective surface of each of the microstructures and the main surface of the body. The first angles of the microstructures in one reflective unit are different from the first angles of the microstructures in an adjacent reflective unit.