Abstract: In this paper, a heavy gear is taken as the research object to carry on the finite element analysis, on this basis, the genetic algorithm multi-objective optimization to the original design gear is conducted so as to improve the gear pair deformation and the force condition. The results show that the main failure area of heavy gear is the meshing part of gear, which is often the position of maximum deformation and maximum force. After multi-objective optimization, the deformation can be reduced by 0.000 16 m, the stress value can be reduced by 1 622.544 MPa, and the gear pair volume can be reduced by 488.921 5e⁴ mm³. It can be seen that the multi-objective optimization method is effective in reducing the deformation, stress and volume of heavy-duty gears.