In order to improve the power level of inverter, improve the waveform quality of the output voltage. In this paper, the topological and corresponding PWM carrier modulation control methods of cascade H bridge multilevel inverter are proposed. The method according to the traditional mixed frequency carrier modulation principle, adopted in phase overlap triangle carrier modulation, a combination of in-phase cascading triangular carrier modulation good harmonic elimination characteristics and the advantages of each unit power natural equilibrium, the cascade multilevel inverter topology H bridge not only can output the multilevel structure, can avoid mixed modulation power circulation problems, and modular inverter is simpler, can be implemented in an output cycle power balance. Taking two high and low pressure units as an example, the simulation experiment was carried out. The experimental results verify the feasibility of the topology and its control method.