对35CrMo钢进行860℃淬火和不同温度（450，500，550，600℃）回火热处理，采用万能试验机、扫描电子显微镜等研究了回火温度对该钢显微组织、拉伸性能与断裂韧性的影响。结果表明：随着回火温度的升高，过饱和α相中析出碳化物并发生球化，马氏体板条状特征逐渐消失；试验钢的屈服强度和抗拉强度均随着回火温度的升高而降低，伸长率增大，当回火温度为600℃时，其抗拉强度、屈服强度、伸长率分别为1 014 MPa，933 MPa，16.8%；随着回火温度的升高，试验钢的断裂韧度增加，断口启裂区由快速启裂扩展特征变为更明显塑性变形特征。

35CrMo steel was quenched at 860 ℃ and then tempered at different temperatures (450, 500, 550, 600 ℃). The effect of tempering temperature on microstructure, tensile properties and fracture toughness was studied by universal testing machine and scanning electron microscope. The results show that with the increase of tempering temperature, the carbides precipitated from supersaturated α phase and were sphericized, and the lath feature of martensite disappeared gradually. The tensile strength and yield strength of the tested steel both decreased,while the elongation increased with the increase of tempering temperature. The tensile strength, yield strength and elongation of the tested steel tempered at 600 ℃ were 1 014 MPa, 933 MPa and 16.8%, respectively. With the increase of tempering temperature, the fracture toughness of the tested steel increased, and the fracture initiation zone changed from rapid crack initiation and propagation characteristics to more obvious plastic deformation characteristics.