Abstract: A circuit model is built to simulate the performance of the Dragon-Ⅱs induction cavity filled with the amorphous magnetic cores. The equivalent capacitances which correlate with the cavity structure are figured out, and the parameters of each magnetic cores circuit module are fixed on by modulating these parameters to make the simulation waveforms match the experiment voltage and current waveforms. With these initialized parameters, the circuit model can simulate the process of the cavitys excitation exactly. The detail of the voltage and current in different positions of the induction cavity, which cannot be probed in experiment, can be worked out by circuit simulation, and it is much useful for structure optimization and fault analysis of the cavity.