In this paper, the heat treatment process of carburizing and quenching of 20CrMnTi steel gear was simulated by DEFORM?HT software, and the carbon mass fraction change from the surface layer to the core after carburization was obtained. The changes in the martensite structure after quenching were analyzed, the residual stress after quenching was analyzed, the appropriate quenching cooling medium was selected, and the metallographic structure and the Rockwell hardness from the surface to the core were measured through experiments. The results show that the metallographic structure and Rockwell hardness are in good agreement with the simulation results, which have certain guiding significance for production.