Abstract: By adjusting the amount (30, 50, 100, 150 μL) of aqueous ammonia, 4 composites composed by iron disulfide and reduced graphene oxide (rGO) FeS₂(30)/rGO, FeS₂(50)/rGO, FeS₂(100)/rGO, and FeS₂(150)/rGO) were synthesized by hydrothermal method with ferric chloride and rGO as the main raw materials. The composite was dropped onto the surface of carbon cloth electrode to prepare FeS₂/rGO modified carbon cloth electrode. MFCs anode was constructed by the modified carbon cloth electrode, and the active Escherichia coli culture medium was added into the anode solution as MFCs anode biocatalyst. MFCs cathode was constructed with carbon paper flakes, and dual-chamber MFCs were formed combined with anodes, to investigate the electric production performance of MFCs. It was shown that FeS₂/rGO was the self-assembled microsphere consisting with thin nanosheet structured rGO and a mixture of sheet-like marcasite FeS₂ and pyrite FeS₂ or a octahedral pyrite FeS₂. After modifying the carbon cloth electrode with FeS₂/rGO, the power generation of MFCs anode was improved to varying degrees. Among them, the maximum power density of MFCs anode made of FeS₂(50)/rGO at a scan rate of 1.0 mV·s⁻¹ could reach 2 984.8 mW·m⁻², which was 1.7 times and 2.5 times than that of MFCs anode made of rGO or bare carbon cloth, respectively. As found by results of tests of cyclic voltammetry and electrochemical impedance spectroscopy, the carbon cloth electrode modified by FeS₂(50)/rGO had a larger electroactive area, and the extracellular electron transfer efficiency between FeS₂ (50)/rGO and active Escherichia coli was higher. The synergistic effect of the two improved the power density of MFCs.