Disclosed are a slit grating and its manufacturing method, a grating structure and a display device. The slit grating includes a plurality of light-shielding regions and a plurality of light-transmitting regions which are arranged alternately. A photochromic layer, which turns to be in a light-shielding state when it is irradiated by ultraviolet light, is arranged at the light-shielding region. A transparent ultraviolet light-absorbing layer, which is configured to absorb the ultraviolet light, is arranged on the light-transmitting region.