Abstract: By establishing the mathematical model of the gas supply system of cathode gas supply system of proton exchange membrane fuel cells（PEMFC）cathode,this paper analyzed the influence of the voltage of air compressor and the opening of back pressure valve on the net power output of the system. According to the change of load power,the oxygen excess ratio and cathode pressure corresponding to PEMFC system were studied,and the optimization table of maximum output net power-oxygen excess ratio-cathode pressure was established.Considering the coupling relationship between the oxygen excess ratio and the cathode pressure,based on the identified transfer function matrix,a feedforward decoupling controller was designed for the voltage of the air compressor and the opening of the back pressure valve to optimize the oxygen supply and pressure control. The simulation results show that the proposed decoupling controller can effectively reduce the influence of coupling,achieve the maximum net power closed-loop control,and has faster response speed and smaller overshoot.