Based on the vibration model of a piezoelectric crystal along thickness direction, the resonance frequency and antiresonance frequency of the piezoelectric ultrasonic transducer with surface silver plating are obtained by the equivalent circuit method, and the results are in agreement with that obtained from the measured results. Taking into account the influence of the coupling layer, the equivalent circuit model of the ultrasonic wireless power transmission channel composed of an external piezoelectric transducerthe metal wallan internal piezoelectric transducer has been established and the impedance characteristics of the channel are simulated. The simulation results are compared with the measuring results using a high precision impedance analyzer and the model is verified to be accurate.