The megawatt level offshore wind turbine gearbox is easily affected by the time-varying non-torque load. Aiming at this problem, this paper proposed a multi-wind speed condition optimization method for the planetary load sharing performance of the gearbox. By establishing the dynamic model of a 5 MW wind turbine gearbox system, the influence of wind speed conditions on the internal excitation and load sharing performance of the planetary was analyzed. Then, the support vector regression method was used to reconstruct the mapping relationship among wind speed conditions, gear modification parameters and load sharing coefficient. The optimization model of load sharing coefficient of the planetary considering the influence of different wind speed conditions was built to realize the optimization design of gear modification parameters. The results show that the time-varying non-torque load caused by wind speed conditions will produce the partial load on the tooth surface and bearing of the planetary stage, and it will significantly reduce the load sharing performance of the planetary stage at low wind speed conditions. Under different wind speeds, the internal excitation of the optimized wind turbine gearbox at the planetary stage is significantly reduced, and the tooth surface and bearing load distribution are more uniform, and the load sharing performance is significantly improved.