Abstract: Taking 2Cr10NiMo alloy steel as the research object, the quenching temperature of the alloy steel was determined by DSC curve, and the effects of different tempering temperature on its microstructure and properties were studied.The results show that, after 1050 ℃oil quenching and water quenching, the microstructure is martensite+a small amount of retained austenite. With the tempering temperature rising from 200 ℃to 350 ℃, the hardness decreases from 49.5 HRC to 46.2 HRC, and the impact toughness increases first and then decreases. 350 ℃tempering, the alloy steel generates low temperature tempering brittleness. 250 ℃tempering, the fracture surface of impact specimen has a large number of dimples, belong to ductile fracture. The wear resistance of the hot-treated alloy steel is similar to that of as-cast, and the wear mechanism is mainly micro-cutting.