First of all, the state space method is adopted to establish the super capacitor two-way Buck DC/DC converter circuit model and the mathematical model of application switch cycle average and euler"s formula to analyze it, and the introduction of small signal disturbance, disturbance and separation after linearization design Buck circuit model of the control method of the double closed loop control strategy. Finally simulink is built to verify the correctness and feasibility of the control strategy, the results provide reference to apply and research for super capacitor.