The invention belongs to the technical field of sewage degreasing and relates to a sewage degreasing agent which comprises urea, carbon disulfide, a sodium hydroxide solution, triphosphoric acid, nonylphenol polyoxyethylene ether, fatty alcohol-polyoxyethylene ether, polyethylene glycol octylphenol ether, triethanolamine oleate, alkali liquor, an additive, sodium aluminate, a mixture of sodium tripolyphosphate and sodium gluconate, and water. The sewage degreasing agent is prepared from the following components by weight: 40 to 135 g of urea, 100 to 250 g of carbon disulfide, 250 to 300 g of sodium hydroxide solution, 6 to 10 g of triphosphoric acid, 30 to 50 g of nonylphenol polyoxyethylene ether, 50 to 100 g of fatty alcohol-polyoxyethylene ether, 10 to 30 g of polyethylene glycol octylphenol ether, 20 to 50 g of triethanolamine oleate, 80 to 400 g of alkali liquor, 5 to 65 g of additive, 60 to 80 g of the mixture of sodium tripolyphosphate and sodium gluconate and a proper amount of water. Theflocculation speed of thedegreasing agent is high, the degreasing agent can flocculate within several seconds, does not contain any metal ions such as aluminum and iron, does not contain PAM, has no viscosity, is easy to backwash, can improve the degreasing efficiency and effect, and can well protect equipment when used.