This paper summarizes the basic module of power transform circuit through the research of the various inverter circuits, and gains the essence of power transform system. It analyzes the advantages and disadvantages through the research of voltage-source inverter and current-source inverter, and points out the characteristics of the circuit. The circuits are explained with the essence of power transform system. The unique characteristics different from other inverter of the Zsource inverter are analyzed. At last, the modules of a power electronic circuit which contains inductive module and switch module as well as diode module are proposed by the comparison of the differences among the three inverter circuits.