Abstract: The effects of different temperature and time of cryogenic treatment on the microstructure and wear properties of 65Mn steel were studied by XRD, SEM, hardness tester and friction and wear tester.The results show that with the increase of deep cryogenic treatment time and the decrease of temperature, the carbon content of martensite in 65Mn steel decreases first and then increases, and the effect of deep cryogenic treatment time on carbon content is more significant.The microstructure of martensite, cementite and troostite are refined.The hardness of 65Mn steel increases at first and then decreases.65Mn steel is mainly worn by abrasive grains and accompanied by adhesive wear.The friction coefficient of 65Mn steel increases slightly after deep cryogenic treatment, but the wear rate is significantly reduced.