The zero-voltage switching of the inductive power transfer system can reduce the inverter loss and improve the transmission efficiency of the system. The soft switching characteristics of the system are usually affected by the system parameters and the equivalent input impedance of the rectifier. However, the existing research on the parameter design of LCC-S topology only regards the rectifier and the back end as a pure resistance, which reduces the accuracy of the circuit model. Based on the LCC-S IPT system, this paper first reveals the fact that the equivalent load of the rectifier contains inductance components, and then explores the variation of the equivalent resistance and equivalent inductance of the rectifier with the system load. Next, the rectifier and back-end of the LCC-S IPT system are equivalent to a circuit model with a resistor and an inductor in series. On this basis, the formula of the system input impedance angle is derived, and then a parameter design method considering the equivalent load model of the rectifier is proposed. Finally, the Simulink simulation platform is built for verification.