An optical film comprising a first surface and a second surface is provided and the first surface and the second surface face in opposite directions. The first surface is disposed with a plurality of first microstructures and a plurality of second microstructures, which are closely adjacent to each other. The first microstructures are upwardly convex quadrangular pyramid structures or triangular pyramid structures, while the second microstructures are downwardly concave quadrangular pyramid structures or triangular pyramid structures.