A new type of bidirectional DC-DC converter with a coupled inductor was designed for the output voltage of the fuel cell power generation system and the input current rod wide. The supercapacitor was used to reduce the impact of current ripple to the fuel cell to increase its power generation efficiency, and improved the output voltage gain by changing the number of turns ratios of the duty ratio and the coupled inductor. A simulation model was created in the Matlab/Simulink software, and a control circuit was built with average current mode. The switching status and working characteristics of the converter were analyzed in the boost and buck mode. The simulation results showed that the input current ripple wave of the converter was about 1%, and the boost voltage gain was up to 16 when the coupling inductance ratio was 1. The results showed that the proposed converter could meet the low frequency current ripple requirements of fuel cell power generation system and achieve high voltage gain at the same time, which verified the feasibility of the proposed topology.