Abstract: To improve the power output density in benthic microbial fuel cells(BMFCs),pyrocatechol violet(PCV) modified graphite anodes were fabricated and their electrochemical properties were studied.Resultsshowed that the contact angle of the PCV-modified graphite anode decreased from 129.1°to 63.3°,and the culturable heterotrophic bacterial cell density on the anode surface increased from 6.8×10⁵/cm² to 1.6×10⁶/cm².The BMFC with modified anode performed better polarization behavior.The exchange current density(i₀) increased from 1.337×10^-3 A/m² to 2.999×10 A/m² and the kinetic activity was improved greatly.The maximum power density(P_m) increase from 28.5 mW/m² to 55.1mW/m².PCV is a kind of biologically active molecule and the acceleration role of PCV in electron transfer between anode and attached bacteria to increase cell performance was analyzed.