Metal mask plate and coating method thereof

The invention provides a metal mask plate and a coating method thereof, different surfaces of the metal mask plate are coated to form insulating film layers, and the coating method specifically comprises the following steps: forming an upper surface insulating film layer on the upper surface of the metal mask plate, and forming a lower surface insulating film layer on the lower surface of the metal mask plate; wherein the nominal thickness of the lower surface insulating film layer is larger than that of the upper surface insulating film layer, and the thickness difference is 10%-40% of the thickness of the upper surface insulating film layer; the metal mask plate is at least used for forming a packaging layer in an OLED production process. Compared with the prior art, according to the scheme, the deformation of sagging/opening morphology occurring in the film coating process and/or after film coating of the metal mask plate can be obviously optimized. And in an ideal state, the net surface sagging morphology