Abstract: The results of mechanical properties testing of ZG15Cr2Mo1 steel were quite different. Two sets of samples with different mechanical properties were analyzed by room and high temperature mechanical test, chemical composition analysis and metallographic examination, and the reasonable heat treatment process was determined. The results show that the main reason for great difference in mechanical properties of the steel was different microstructure caused by unstable heat treatment process. Normalizing at 920-970℃ for 8-12 h and tempered at 720-760℃ for 8-12 h could make the structure of the steel uniform and obtain better comprehensive mechanical properties.