Abstract: The three-dimensional eight-degree non-linear dynamical model of the spiral bevel gear was established based on the lumped mass method.Time-varying mesh stiffness,non-linear geometric transmission error,gear clearance and non-linear bearing stiffness were considered in this model.The dynamic response for the transmission system was solved by using Runge-Kutta method.Then,by taking meshing cycle root mean square vibration acceleration as an optimizing object,GA(genetic algorithm) was used to optimize these two local control parameters in the local synthesis,meanwhile optimized machining parameters of the gear pair were also obtained.By the way of tooth surface modification,the purpose of reducing gear's vibration and noise was realized.