A backlight module includes a frame, a reflective sheet, a light guide plate, a light source, and an optical film set. The frame defines an accommodation space, and the reflective sheet is disposed in the accommodation space. The light guide plate is disposed in the accommodation space and on one surface of the reflective sheet. The optical film set is disposed one side of the light guide plate opposite the reflective sheet. The reflective sheet is hollowed out at a position overlapping the light source to form at least one opening so as to reduce light halos.