The present disclosure relates to a manufacturing method for a metal grating, a metal grating, and a display device. In this manufacturing method, after forming a plurality of parallel grating strips by means of an adhesive film layer, a metal thin film with a uniform thickness is formed over the plurality of grating strips and gaps between the grating strips. Furthermore, a metal grating is formed by performing topping treatments on both of an upper surface and a lower surface of the resulting structure.