Abstract: The different temper temperatures which affected the microstructure and mechanical properies of 25Cr2MoVA steel after quenching at 900℃ were studied in this paper. The result indicated that 25Cr2MoVA steel has high temper resistant stability after quenching and tempering. When the temper temperature increased above 660℃,it still has high strength and plasticity. When it is tempered below 350℃,the steel still has high temperature strength and extensibility.