The back-up power is the core of the substation DC system in power system.Based on the reliability of the back-up power, the method of double Boost the Boost converter is proposed in this paper.To prevent the DC power supply module parallel running when the circulation and current uneven phenomenon, the intermediate current-sharing method is adopted that the booster power supply module in parallel is achieved.The corresponding simulation model is established through the MATLAB/simulink simulation software. From the corresponding simulation we can achieve that the double Boost booster method is both a kind of effective method of booster and an effective method to reduce the power components of current stress in the circuit.The intermediate current-sharing method can realize the steady state flow control and ensure the power supply module can be continuously electricity for replacement in the case of malfunctions.