A sprue cup for smelting alloy mainly consists of an inner cup wall, an outer cup wall and a bottom plate shared by the inner cup wall and the outer cup wall; four dams are arranged between the inner cup wall and the outer cup wall; all dams are positioned between outlets of molten liquid channels and filtering ports; the outlet of each molten liquid channel is positioned between the adjacent dams; each dam is provided with a slag blocking channel; the slag blocking channel at the inner side surface of the dam is provided with the inlet of the slag blocking channel; the outer side surface of the slag blocking channel is provided with the outlet of the slag blocking channel; and the highest point of the inlet of the slag blocking channel is lower than the lowest point of the outlet of the slag blocking channel. The sprue cup can better control the impurity content in alloy solution, and improves the quality of the alloy smelt by vacuum; and compared with the original sprue cup, the impurity content in the produced mother alloy is reduced obviously.