Abstract: The influence of high vacuum heating and convection heating with high purity nitrogen and high purity argon gas protection when aged in vacuum tempering furnace on the properties of PH15-5 precipitated hardening stainless steel is investigated. The results show that better sarface brightness could be obtained, but mechanical properties were more dispersed with high vacuum heating and mechanical properties were less dispersed with convection heating. The brightness of PH15-5 was higher with high purity nitrogen heating than with high purity argon heating.