The invention discloses a cold-rolled oil sludge degreaser and a use method thereof. The cold-rolled oil sludge degreaser comprises, by weight, 10-20% of a mixed surface active agent, 0-5% of EDTA, 0-5% of sodium metaaluminate, 0-5% of sodium metasilicate nonahydrate, 3-10% of sodium borate, 0-6% of sodium pyrophosphate and the balance of water. The method includes the steps that 1, the degreaser and cold-rolled oil sludge are fully and evenly mixed to form a mixed solution, and accordingly grease in the cold-rolled oil sludge is extracted through the degreaser, wherein the use amount of the cold-rolled oil sludge degreaser in per kilogram of cold-rolled oil sludge is 1.2-3L; 2, the mixed solution stands still for 1.5-2.5 h, then the mixed solution is filtered, the grease is filtered out, and super-fine iron is separated. By means of the degreaser, the grease in the cold-rolled oil sludge is washed, and micro-iron and nano-iron are separated out. Disposal cost of hazardous waste is reduced, ultra-fine iron products with high additional value are obtained, and the problem that ore grease degreasing efficiency in the cold-rolled oil sludge is low is solved.