The invention provides a mask plate, a substrate and a display device, relates to the technical field of display, and solves the problems of uneven upper surface and existence of angle section difference in the colorful film layer formed by the existing mask plate. The embodiment of the invention provides a mask plate which comprise a whole transmission area, a partial transmission area and a non-transmission area, wherein the mask film is divided by the non-transmission area into exposure units arranged in a plurality of arrays; each exposure unit comprises the whole transmission area and the partial transmission area; the partial transmission area is arranged between the whole transmission area and the non-transmission area; the exposure units of the mask plate are correspondingly formed into film pattern units; the height of films formed by the whole transmission area of the exposure units is greater than that of films correspondingly formed by the partial transmission area.