Abstract: For rail transit non-contact power supply system, when the relative position between the receiving coil on vehicle and the transmitting coil on track changes, the energy transmission efficiency of the system changes. Maxwell software is used to establish a three-dimensional model of the transmitting coil and the receiving coil, and the parameters such as self-inductance and mutual inductance of the coils are simulated. The system simulation model based on SS topology structure is built by Simplorer to obtain the transmission efficiency of the power supply system under different working conditions. Influence of different road conditions on the non-contact power supply system is analyzed in-depth.