Abstract: In order to solve the severe problem of mechanical vibration, audible noise and electromagnetic interference resulting from the prominent amplitude harmonic, the random space vector pulse width modulation has important application prospects and has been widely discussed. The random switching frequency PWM technique has the most excellent performance among several types of random strategies. Aiming at the spectrum spreading performance, the study simulates and discusses the random switching frequency pulse width modulation of the two-level three-phase inverter. The two factors-switching frequency range width and probability distribution law-that affect the spreading effectiveness are analyzed in theory based on the theoretical spectra expression. The switching frequency range width factor in theory is consistent with the experiment result. The simulation verifies the theoretical analysis. The simulation shows that it is feasible to find an optimal probability distribution law that can improve the spectrum spreading effectiveness.