Embodiments of the present disclosure relate to a prism film, a backlight module, and a display device. The prism film includes a substrate and a plurality of prisms on a surface of the substrate, each of the plurality of prisms having a triangular cross section, and having a first optical surface, a second optical surface, and a third optical surface that are perpendicular to the triangular cross section, wherein the first optical surface is parallel to the surface of the substrate, the first optical surface and the second optical surface form a first bottom angle, the first optical surface and the third optical surface form a second bottom angle, and at least one of the first bottom angle and the second bottom angle of the plurality of prisms gradually changes.