Abstract: A novel anode, with carbon felt (CF) which was electrodeposited with conductive polymer polythiophene (PTh) and Lmethionine (L-Met) added into sea mud, was creatively fabricated to construct marine sediment microbial fuel cells (MSMFCs), and electrochemical performances of the MSMFCs with the modified anodes were investigated. The results show that the amount of microorganisms attached to the modified anode is 11. 3 times of that of the unmodified one and the biofilm capacitance of modified anode is 1. 4 times of that of the blank anode, indicating that the modification can help to increase the number of microorganism attached to the anode. Furthermore, the specific capacitance of the modified anode (302. 6 F/cm²) is 8. 0 times of that of the blank anode (38. 20 F/cm²), with a peak current of about 5. 980 A/m². The exchange current density of modified anode (48. 29 × 10^-3 m A/cm²) is 651. 3 times of that of the blank anode (0. 073 7 × 10^-3 m A/cm²), illustrating sigificant improvement in electrochemical activity of redox, anti-polarization capacity and electron transfer kinetic activity. The output power of the modified MSMFCs (190. 6 m W/m²) is 2. 7 times of that of the blank group (71. 8 m W/m²), which suggests that the modification improves the electrochemical performance of the anode and the battery performance.