Permanent magnet synchronous motors (PMSM) have been widely used in electric vehicles due to their high efficiency and high-power density. However, due to the non-sinusoidal characteristics of the air-gap magnetic field distribution and the cogging effect in PMSMs, the torque ripple problem of the motor is induced, which in turn causes motor vibration and noise. In order to reduce the torque ripple and its adverse effects, an asymmetric rotor auxiliary notch structure is proposed and optimized in this paper. With the optimization objectives of minimizing torque ripple and radial electromagnetic force of the motor, a high-precision motor performance prediction model is established by the finite element method, and the asymmetric rotor auxiliary notch are quickly calculated and optimized by a genetic optimization algorithm. The optimization results show that compared with the reference motor model, the optimized model has basically the same output torque under specific operating conditions, the torque ripple has been reduced by 27.9%, and the maximum noise of the motor has been reduced by 4.85 dB from 87.49 dB to 82.64 dB. This study provides a practical and effective solution for suppressing the torque ripple of PMSM.