Aiming at electromagnetic interference generated by the inverter of the electric vehicle, proposed a random center position modulation method. On the basis of the original seven segment symmetry modulation, the method moves around the center position of the pulse in the modulation cycle and changes the pulse time randomly within a certain range in order to achieve random center location modulation. With Matlab/Simulink established a simulation model for vector control of permanent magnet synchronous motor. The simulation results show that comparing with the conventional seven segments symmetrical modulation, random center position modulation can reduce the carrier frequency and carrier-fold harmonic amplitude of frequency, there by reducing the inverter external electromagnetic radiation interference.