The present invention provides a backlight module, comprising an optical film assembly, a light guide plate, a reflective sheet, and the optical film assembly comprises a first prismatic glass, and the first prismatic glass comprises a display region, two side walls, a junction region, and the display region and the reflective sheet are oppositely located, and the side wall is formed by the display region extending downward, and the side wall is connected between the display region and the junction region to form an accommodation space, and the light guide plate and the reflective sheet stack up together inside the accommodation space, and the light guide plate is located between the reflective sheet and the optical film assembly, and the reflective sheet is located between the light guide plate and the junction region.