Abstract: The heat treatment process of carburized parts（carburizing temperature, holding time, quenching medium,tempering temperature and cold treatment） can obtain different amounts of residual austenite. If 18Cr2Ni4WA is directly quenched after deep carburizing, it will lead to a large amount of residual austenite on the surface, and the surface hardness is 50～55HRC. Multiple high temperature tempering is required to reduce the amount of residual austenite. This kind of tempering period is long and the equipment utilization rate is low. For heavy duty large gear parts with carburizing layer depth ≥3.0mm, the high temperature tempering process of 660～680℃ is adopted to reduce the amount of residual austenite and meet the technical requirements. This process is a preliminary heat treatment procedure of 18Cr2Ni4WA heavy duty gear, which provides a good original structure for the final heat treatment of heavy duty gear.