A gear modification method for wind turbine gearbox is proposed aiming at achieving minimum dynamic transmission error（DTE）.Firstly

a multibody dynamics model for the gearbox is established by using the substructure synthesis

in which the gearbox is divided into a planetary stage

a high-speed and a lowspeed parallel helical gear stages.By using the multibody dynamics model

the simulation of dynamics and meshing characteristics of the overall system are obtained.The simulated results include the DTEs

the damage rates as well as safety factors of each gear.Based on the above simulation results

a three-dimensional gear modification study is carried out by taking minimum DTE as optimization objective and the reliability of gear as constraint condition.The tooth profile and longitudinal modification parameters matching schemes are determined through orthogonal experiment principle.The simulations results indicate that using the proposed modification scheme

the DTE can be drastically decreased and the load distribution on gear surface can be effectively improved

thus ensures a high reliability of the transmission.