Abstract:for 6k order torque ripple of PMSM which causes the body structure vibration and noise in distributed drive electric vehicle, a new calculation method of the electromagnetic torque for PMSM in distributed drive is presented. According to distortion of field in PMSM, radial flux density of permanent magnet in uniform air gap is expanded to Fourier Series. By means of calculation of magnetic flux linkage and voltages, analytic expression of electromagnetic torque is finally obtained. Therefore, this paper explains in theory 6k order( )vibration of PMSM for distributed drive. According to spectrum analysis and order analysis, it proves that torque tipple frequency tends to be proportional to pole pairs and rotate speed. At the last, the analytic calculation result is tested and verified by means of the finite element.