Resonant coupling wireless power transfer mode can be used to transmit energy in middle distance, which is a new type of energy transmission. In this paper, aiming at the problem of the resonant coil’s optimal design, taking equivalent circuit model of two coils of wireless power transmission system as example, the influence of resonance and mutual inductance on the transmit power and efficiency of the system is analyzed in details, then proposesSa method for optimizing the resonator with the transmission power and efficiency of the system. At last, combined with the example simulation, designed several group parameters of resonant coils comparison experiment, the results show that, exchange two resonant coils" parameters under the resonant state, the transmission power and efficiency of system remain unchanged basically, thus proves the effectiveness of proposed method.