To simplify the complex parameter design process and reduce the switching loss of CPT (capacitive power transfer) system with a LCL resonant circuit, we proposed a simple parameter design method based on impedance transformation principle and presented a calculation method for the soft-switching frequency. With the stroboscopic method and the fixed-point theory, the precise ZCS (zero current switching) soft-switching frequencies can be calculated. The effect of the coupling capacitance and the load resistance on the soft-switching frequency was analyzed, and then the capacitance and the load range allowing the soft-switching were given. A simulation model and an experimental prototype were built to verify the accuracy of the parameter design and the soft-switching frequency. It shows the whole efficiency of the system is about 87%.