Casting method and casting device for valve body with waterline surface

The invention discloses a casting method and a casting device for a valve body with a waterline surface, and relates to the field of valve body casting. According to the casting method, molten metal is guided into a casting cavity, in the solidification process of the molten metal, a first flange and a second flange are fed through a riser base cavity, and the molten metal stored in a first riser in a riser system is supplemented to the riser base cavity; the waterline part on the inner side is fed through the peripheral side of the first flange, and the waterline part is partially solidified before the peripheral side of the first flange, so that the casting quality of the waterline part is guaranteed; a metal patch arranged between a waterline flange and a low-position structure is replaced by the riser seat cavity, so that the reject ratio of crack defects generated at the joint of the riser seat and a required casting is reduced. The casting quality and precision of the inner circumferential side part of