NOVELTY - Cyclic utilization of potato slag and wastewater comprises crushing prepared crop straws of the filtering assisting absorption materials taken as the first filtering assisting absorption material; and making the porous minerals to be the second filtering assisting absorption material; filtering the potato slag and/or wastewater; filtering the filtrate added with the first filtering assisting absorption material; making the filter residue to raw materials of feed after drying or fermenting; and filtering.    USE - Method for cyclic utilization of potato slag and wastewater used in manufacturing potato starch (claimed).    ADVANTAGE - The method can purify wastewater, and the purified water can be used for washing in the potato processing directly or after depositing.    DETAILED DESCRIPTION - Cyclic utilization of potato slag and wastewater comprises:    (A) crushing prepared crop straws of the filtering assisting absorption materials to particles of 1-30 mm taken as the filtering assisting absorption material 1; and making the porous minerals which can be taken as feed additive to particles of 0.1-5 mm to be the filtering assisting absorption material 2;    (B) filtering the potato slag and/or wastewater, and obtaining filtered slag and filtrate, where the mass ratio of the potato slag to the wastewater in the mixture is 1:0.1-5;    (C) filtering the filtrate added with the filtering assisting absorption material 1, where the thickness of the material layer added with filtering assisting absorption material 1 is 20-80 cm, and producing filter residue and filtrate;    (D) making the filter residue obtained in steps (B) and (C) to raw materials of feed after drying or fermenting; and    (E) filtering the filtrate obtained in step (C) added with the filtering assisting absorption material 2, where the thickness of the material layer added with filtering assisting absorption material 2 is 8-50 cm, and the filtrate obtained can be used for washing in potato process or enter the water quality purifying system.