Abstract: The effects of aging treatment on microstructure and mechanical properties of martensite precipitation hardening stainless steel 06Cr15Ni5Cu2 Ti were studied by means of phase diagram calculation,tension test,optical microscope,scanning electron microscope and transmission electron microscope.After solid solution at 1 000 ℃,the aging treatment was conducted at different temperature varying from 425 ℃ to 650 ℃.The results show that the steel has peak strength but minimum impacttoughness valueat aging temperature of 450 ℃.As the aging temperature increases,the strength of the steel decreases,but the impact toughness gradually increases.At aging temperature of 650 ℃,the lowest strength appears and the impact energy reaches the highest.This is mainly related to the occurrence of copper-rich phase and reverse transformation of austenite in the structure.Considering the strength and toughness,06Cr15Ni5Cu2 Ti steel can achieve a goodcombination of strength and toughness when it is aged at 500 ℃.