This article summarized the research progress on the theories of laser quenching, and meanwhile analyzed the formation mechanism of hardening layer, as well as its difference from the formation mechanism of the traditional gear quenching methods. Through the analysis of scanning way, offset, scanning speed, angle of incidence and auxiliary cooling technology in the process of laser quenching, corresponding optimization schemes were put forward. By comparing the hardness of tooth surface, wear resistance, deformation, the microstructure and grain shape and distribution of the gears treated by laser quenching and normal quenching, it was concluded that the gear product of laser quenching had better mechanical performance than those prepared by the conventional quenching.