Wheel drive motor torque ripple will cause noise and vibration, and affect vehicle ride comfort. The research status of electric vehicle wheel drive systems was described briefly. Based on the analysis and comparison of several electric vehicle motor, The causes of torque ripple in permanent magnet DC motors were summarized. Preventive measures of the torque ripple were proposed accordingly. Finally to be proposed were the new questions of the torque output characteristic of BLDC while used as the wheel drive motor in complex driving conditions.