Aiming at the problem of excessive torque fluctuation of double-layer permanent magnet synchronous motor (PMSM) for vehicle, based on the evolutionary algorithm (EA), the parameters of rotor skew angle, stator slot height, stator slot width and width and thickness of double-layer magnet steel for a double-layerpermanent magnet synchronous motor (PMSM) applied to dedicated hybrid transmission (DHT) were optimized. The sensitivity of each parameter was analyzed by design of experiment (DOE) method to derive the influence weights and positive and negative correlations of the parameters on the optimization target, and then the optimal parameter combination was derived by combining with the multi-round EA, and the results showed that the torque fluctuation of the optimized PMSM decreased by 3.5%. In addition, the maximum torque per ampere (MTPA) control of the optimized PMSM was simulated by joint simulation, and the results showed that the torque fluctuation of the optimized motor is obviously reduced in the high torque speed-up stage, which verified the effectiveness of the optimization process. The simulation process improves the efficiency of the optimization process, reduces the number of physical tests, and lowers the development cost and development cycle for DHT.