A backlight module is provided. The backlight module includes a substrate; a plurality of light-emitting elements, disposed on the substrate along a first direction and a second direction; and at least one optical film, including: a first surface, having a plurality of cone structures, top points of the cone structures being arranged to form a plurality of first ridges. In addition, an angle is between the first ridge and the first direction; and a second surface, corresponding to the first surface and toward the substrate, the plurality of light-emitting elements being between the substrate and the second surface.