Abstract: A circuit model of magnetically-coupled resonant wireless power transmission system was established, and relationships between transmission power, transmission efficiency and input frequency, transmission distance and load were analyzed. The simulation and experimental results show that transmission power and transmission efficiency achieve the maximum when input frequency of the system is the same as resonant frequency of excitation coil loop without frequency offset; transmission power increases then decreases with increase of transmission distance, and there is the optimum transmission distance to get the maximum transmission power, while transmission efficiency increases with decrease of transmission distance; transmission power and transmission efficiency increases then decreases with increase of load, and there is the optimum matched load to get the maximum transmission power and transmission efficiency.