A method for patterning a film, and a display device and preparation method therefor. The method for patterning a film comprises: forming a magnetic material pattern inside a flexible substrate to obtain a magnetic substrate (S100); placing the magnetic substrate on the surface of the side of a film to be treated against a first rigid substrate, wherein the film to be treated and the first rigid substrate are provided opposite to and spaced apart from each other (S200); applying a magnetic field to the magnetic substrate, such that the magnetic material pattern pushes, by means of a magnetic action, the part of the film to be treated corresponding to the magnetic material pattern towards the first rigid substrate and attaches same to the first rigid substrate (S300); and removing the magnetic field, the magnetic substrate, and the part of the film to be treated that is not pushed towards the first rigid substrate, so as to form a patterned film on the first rigid substrate (S400).