Abstract: Two sine pulse width modulation （SPWM） trigger pulse generating methods were analyzed based on symmetry regular sampling and irregular sampling, then a carrier phase-shifted sine pulse width modulation （CPS-SPWM） pulse generating time sequence for cascaded H-bridge multilevel converters was produced. This paper proposed a new trigger pulse quick generating method on the basis of the irregular sampling. Based on this method, the fundamental characteristics of the output voltage of cascaded H-bridge multilevel converters were studied. Via theoretical analysis, simulations and experimental validation of this method, it shows that, compared with the pulse generating method based on symmetry regular sampling, this method needs neither to increase the sampling frequency, nor to add the amount of calculation. Furthermore, about the SPWM output voltage based on the new method, the delay-time of its fundamental component which only lags the modulation wave a quarter of carrier wave period, is shorten by 50 percent, its amplitude is higher, and the asymmetry of the voltage is improved greatly.