Abstract: The marine sediment microbial fuel cells (MSMFCs) have been constructed with three types of anodes: unmodified anode (blank control), ammonia modified anode and NH₄HCO₃ modified anode by electrochemical oxidation. The influences of the ammonia modified anodes on electrochemical performances of petroliferous MSMFCs are explored and their effects on accelerating petroleum degradation are investigated. The results show that the electrochemical performance of the anode modified by NH₄HCO₃ is 1.78 times that of the blank control, and its electrochemical activity and polarization resistance are optimal. Its exchange current density is 2.57 × 10^-2A·m^-2, which is 5.00 times of that of the unmodified one. The maximum output power density of the MSMFCs with the NH₄HCO₃ modified anode is 1.53 × 10² m W · m^-2, which is 3.56 times more of that of MSMFCs with unmodified anode, and its petroleum degradation rate is 10.40 times as high as that of the blank control, for the existence of hydrophilic amide groups and amino groups on the modified anode surface is favorable for the attachment of microorganisms. The electrochemical performance of the MSMFCs with NH₄HCO₃ modified anode by electrochemical oxidation is significantly improved.