Objective The traditional phase disposition PD modulation method has good harmonic performance when applied to cascaded H-bridge inverters but there is an imbalance in output power between different units. To solve the problem of power imbalance while preserving better harmonic performance an improved and optimized modulation strategy was proposed to simplify the control difficulty and at the same time make the inverter power balanced and output a better power quality. Methods Firstly the modulating waveform was optimized to simplify the control. Then the switching signals of each unit were logically operated and the switching signals were redistributed so that the switch conduction time of each unit was equal. Results Simulation of improved and optimized modulation and traditional PD modulation proved that the improved and optimized modulation will not change the output voltage characteristics of traditional PD modulation and the power balance of each unit can be realized. Finally experimental verification was conducted on the improved and optimized modulation. Conclusion The improved and optimized modulation simplifies the control ensures power balance and yields a better output voltage.