The invention discloses a cooling water way for a forming casting mold of a motorcycle cylinder cover. The cooling water way has an upper mold and a lower mold; a forming cavity is formed in a forming surface of the upper mold; a forming mold core matched with the forming cavity in shape is arranged on a forming surface of the lower mold; multiple sets of cooling grooves positioned at the outer periphery of the forming mold core are arranged on the forming surface of the lower mold; cooling assistant grooves narrower than the cooling grooves are respectively formed in the front ends of all the sets of cooling grooves; semicircular flow passing grooves are formed in the cooling grooves; ports of the semicircular flow passing grooves are positioned on the side surface of the lower mold; flow passing holes are formed in the bottoms of all the sets of cooling grooves; a circulating channel communicated with the flow passing holes is formed in the lower mold; and a port of the circulating channel extends to a mounting surface of the lower mold. As the multiple sets of cooling grooves cool the periphery of the mold core and the internals of the molds in the mold forming process, the cooling effect is good, the excellent protecting and cooling effect is achieved on the mold core, the operation can be continued, formed products can be indirectly cooled, the production time is shortened, and the product quality is guaranteed.