The invention provides a split-type mold for wheel casting, the mold having an upper die, a split-type water-cooling side die and a lower die, and the split-type water-cooling side die is divided into four pieces along a circumferential direction of the wheel mold. A thermal deformation arc compensation surface is machined on ¼ arc portion of each split-type water-cooling lower side die, and a compensation surface is machined on key portions of 45-degree matching surfaces of adjacent split-type water-cooling upper side dies. The side die can effectively solve the problems such as untight matching between the matching surfaces, flashes of the matching surfaces and aluminum sticking and the like due to the thermal deformation and non-homogeneous expansion and shrinkage of the two portions of the split-type water-cooling side die.