The present disclosure provides a sealant curing device and a mask plate thereof. The mask plate includes a light transmission region and a light shielding region. The light transmission region includes at least one through hole defined in the light transmission region. After the completion of exposing and curing sealant, at the beginning of the downward movement of the liquid crystal panel away from the mask plate, the presence of the through holes increases an area of air inlet, thereby increasing air inflow and reducing flow speed of intake air, so as to reduce a pressure difference of an air pressure between the mask plate and the liquid crystal panel and an air pressure of ambient air. Under conditions of same action area, a pressure force generated by the pressure difference and applied to the mask plate may be reduced, thereby reducing load for adsorbing the mask plate via vacuum.