Abstract: Polypyrrole/multi-walled carbon nanotubes (PPy/MWCNTs) composite was synthesized by chemical oxidative polymerization method using SDBS as dopant, FeCl₃·6H₂O as oxidant and the composite material is utilized to prepare the anode in marine sediment microbial fuel cell.The electrochemical properties of the modified anode and cell were tested.The results reveal that MWCNTs is tightly coated by polypyrrole and its maximum exchange current density is 0.66 m A/cm², 3.6 times more than the unmodified.The maximum power density of modified cell reaches 408.8 m W/m², 5 times higher than that of the battery unmodified.The modified electrode capacitance is a synergistic result of pseudocapacitive and electric double layer, which greatly improves electrons transfer efficiency and its anti-polarization capability.A new electron transfer mechanism in the interface between the modified anode and biofilm was also presented.