Combining the optimization mathematical theory with Matlab,taking the double circular arc cylindrical gear drive as study object,the optimization design is carried out. During the optimal design process,regarded minimal centre distance and gear volume as optimization goals,the boundary and strength constraint condition is proposed,the optimal design model is established by determining the value of the parameters.Then,the program of the optimization is programmed,the optimization scheme is obtained through the function of fmincon and bnb20. Compared with the original design scheme,the centre distance is reduced by 24%,and gear volume is reduced by 27%,so the effect of optimization is significant,the necessary reference for design and type- selection can be provided.