The new energy vehicle (NEV) motor has strict performance requirements for such parameters as torque density, power density, torque ripple, vibration noise and high efficiency section. Rotor topology and its structural parameters directly affect the magnetic flux density, magnetic field distribution and harmonic magnetic field contents, so they play an important role in the performance of NEV motor. For NEV motor, there are different operating conditions and various performance parameters. Finite element software is used to build the electromagnetic field calculation model for the main operating conditions and determine the structural parameters to be optimized. According to the main performance of vehicle motor, the optimization objective is defined with torque ripple, cogging torque, airgap induced voltage total harmonic distortion (THD) and output torque. The objective function is defined according to the performance requirements of different working conditions, and the genetic algorithm is selected as the multiobjective optimization design algorithm. According to the optimized calculation results, the scheme selection is outlined. Finally, the optimal structure and size parameters of the rotor are determined. The optimization design method can quickly determine the optimal electromagnetic design scheme of vehicle permanent magnet motor and enrich the efficient optimization design approaches of this kind of motor.