The invention provides a preparation method of a polyvinylidene fluoride membrane material. The method comprises the steps that irradiation is conducted on polyvinylidene fluoride, and irradiated polyvinylidene fluoride is obtained; and the irradiated polyvinylidene fluoride and ultraviolet light absorbers are subjected to a grafting reaction, and the polyvinylidene fluoride membrane material is obtained, specifically, the ultraviolet light absorbers are selected from one or more of benzophenone and benzotriazole. According to the preparation method, the polyvinylidene fluoride is pre-irradiated, radicals are generated in molecular chains, the specific ultraviolet light absorbers are further triggered to conduct the grafting reaction, the grafting ratio after the reaction is high, reaction operation is easy, and the experiment conditions are easy to control. The ultraviolet light transmittance of the polyvinylidene fluoride membrane material obtained through modification is low, and influences of the adding quantity of the ultraviolet light absorbers to mechanical performance of the PVDF are small.