The multi-objective optimum model for maximal contact ratio

minimum volume and equal to bending strength of high contact ratio cylindrical gear drive is established

the Pareto optimal solutions are obtained by using a fast elitist non-dominated sorting genetic algorithm（NSGA-Ⅱ）.An example of multi-objective optimization design of high-speed heavy helical cylindrical gear drive is studied

an optimal scheme selected from the Pareto optimal solutions is compared with the original scheme

it shows that bending strength of the optimal scheme is enhanced and volume decreased slightly.