Powder metallurgy (P/M) Inconel 718 superalloy was processed through hot isostatic pressing (HIP) route by SS-PREP powder. Effect of heat treatment on the microstructure and mechanical properties of superalloy was research. The results indicated that the distribution of size of Inconel 718 superalloy SS-PREP powder uniformity, with the fine degree of sphericity. HIP at 1210℃/120MPa for 4h, average size of grain was 50μm, tensile strength at room temperature was 1260MPa. Tensile strength at room temperature achieve to 1404MPa through solution treatment at different temperatures and two-step ageing treatment, and Tensile strength at 650℃ achieve to 1150MPa. Optimum properties of Inconel 718 superalloy appears when solution treatment at 980℃.