Abstract: A grapheme-polypyrrole-cobalt composite electrode was prepared one-step constant potential method. The electrochemical performance of the composite electrode was characterized by cyclic voltammetry and AC impedance technique. The composite electrode was used as the anode and the cathode of the photo microbial fuel cell (PMFC) and the performance of MFC was investigated. The results showed that the modification of GO/PPy/Co greatly increased the capacitance,reduced the charge transfer impedance and improved the electron transfer efficiency of the carbon felt electrode. Also the electrode has good biocompatibility and stability. As the result,the PMFC produced a 3.1 times high power output with a coinstantaneous 76% reduction in internal resistance as compared the PMFC with bare carbon felt electrode.