Abstract: This paper presents a new simulation method for power electronic circuits through the uses of a digital computer. Semiconductor switches are described as binary inductor models, with very low values of inductance during conduction and infinite values of inductance in other case. Also, in the paper, an approach to determine these low values of inductance is presented. The equations are established with modified nodal method, then Backward Euler integration method is employed for the solution of equations to ensure its convergence. With this method, the status of switches can be monitored efficiently, and the changes of topology structure are solved with least amount of computation. In addition, a simulation example is given,with its waveforms presented.