The invention relates to the method for recycling waste slag of fused salt chlorination and belongs to the field of resource recycling. The method for recycling the waste slag of fused salt chlorination comprises the following steps that a, the waste slag of fused salt chlorination is mixed with water, and filter liquor and filter residues are obtained after stirring and filtering, wherein the solid-to-liquid ratio of the waste slag of fused salt chlorination and the water is 1: (3-5) g/ml; b, recrystallization is carried out on the filter liquor to obtain regenerated fused salt slag, wherein the waste slag of fused salt chlorination is obtained during production of titanium sponge or titanium dioxide through a salt chlorination method. The invention further discloses application of the regenerated fused salt slag for improving the grade of artificial rutile. The method for recycling the waste slag of fused salt chlorination is simple in procedure and easy to operate, the obtained regenerated fused salt slag can be applied to production of the artificial rutile, and the grade of the artificial rutile can be improved by 3-6 percent.