Abstract: Effect of aging process on the tensile properties and friction-wear resistance of 17-4 PH martensitic precipitation hardenable stainless steel was studied by scanning electron microscope and energy dispersive spectrometer,Vickers hardness tester,tensile tester,X-ray diffractometer,friction and wear tester. The results showed that(a) as the aging temperature increased,the 17-4 PH stainless steel increased at first and then decreased in both strength and hardness,and increased gradually in plasticity,and the steel exhibited tensile strength as high as 1 377. 2 MPa,yield strength as high as 1 326. 7 MPa,and hardness as high as 462 HV0. 5;(b) the optimal heat treatment practice was solution treatment at 1 040 ℃ for 1 h followed by water cooling,then aging at 480 ℃ for 4 h followed by water cooling;(c) the main wear mechanism was abrasive wear and adhesive wear.The wear resistance of 17-4 PH steel heat treated by the above-named optimal process was 2 times larger than that of 17-4 PH steel heat treated by the original process.