The invention relates to a mask device comprising a mask plate and a shielding member. The mask plate is evenly provided with multiple through holes. The shielding member is connected with the mast plate in an abutting way. The shielding member is provided with a port of which the shape is irregular. The port is aligned with a part of through holes on the mask plate and the port is communicated with all the aligned through holes. The shielding member is arranged on the rest part of through holes on the mask plate in a shielding way. The mask plate is evenly provided with the through holes so that all parts of the mask plate are enabled to have the same mechanical property, the overall deformation of the mask plate is enabled to be consistent and wrinkling can be avoided. Besides, the irregularly shaped port of the shielding member is adaptive to the special-shaped AA region of the display screen, the organic material can be vapor-deposited on the substrate through the port and the through holes aligned with the port in turn and the through holes shielded by the shielding member can effectively shield the organic material so that the special-shaped AA region of irregular shape can be formed on the substrate and the vapor deposition effect of the display screen equipped with the special-shaped display region is enabled to be better.