An optical film for a cover plate of a flexible display, which is disposed on the display side of the flexible display, is disclosed. The optical film sequentially includes an optical substrate layer adjacent to the flexible display, a first adhesive layer, a polarizing layer, a second adhesive layer and a surface functional film which is disposed on the folding side of the flexible display. The optical film having excellent bending resistance and recovery property can be obtained by adjusting the ratio of the integrated bending modulus of the optical substrate layer, the polarizing layer, and the surface functional film to the total thickness of the optical film.