Embodiments of the present disclosure provide a method for producing a mask and a mask obtained by this method. The mask is configured to shield light during an exposure of a product. The method includes steps of: producing a composite membrane, wherein the composite membrane includes a first protection layer, a bonding layer, a shielding layer and a second protection layer stacked in sequence; only cutting the first protection layer, the bonding layer and the shielding layer of the composite membrane, wherein a cutting line corresponds to a shape of an area to be exposed of the product; removing the first protection layer and cut portions of the bonding layer and the shielding layer which have a same shape as that of the area to be exposed; attaching the formed composite membrane onto a base substrate of an open mask, and removing the second protection layer.