Microbial fuel cells (MFC) have the potential of generating electricity and removing nitrogen simultaneously in the treatment of nitrate containing wastewater. It is crucial to find a cathode modified material with low cost and improved performance of generating electricity and removing nitrogen for the commercial application of MFC in the field of wastewater treatment. Cuprous oxide/reduced graphene oxide (Cu₂O/rGO) composite which has the advantages of excellent electrochemical properties, hold a wide application prospect in replace of Pt-based material for improving performance of microbial fuel cells (MFCs). In this study, material characterization and oxygen reduction property were conducted to analyze the synthesis of Cu₂O/rGO composite materials after synthesis by reduction method. The electrochemical performance of Cu₂O/rGO cathode was analyzed after it was loaded on the surface of cathode carbon cloth. The enhancement effect of Cu₂O/rGO cathode on the power generation and nitrogen removal performance of MFC were investigated through the output voltage, power density and NO_3^--N removal rate of MFC. The mechanism of Cu₂O/rGO cathode enhancing MFC performance was investigated by measuring denitrifying enzyme activity and extracellular polymer. Results showed that Cu₂O/rGO which has a large number of mesoporous structures, provide more channels for electron transport, and Cu₂O/rGO has better redox reversibility. Compared with Pt/C cathode, the exchange current density of Cu₂O/rGO cathode increases by 33.53%, the electron transfer resistance decreases by 65.53%. The maximum average output voltage (662.54 mV), maximum power density (26.27 mW/cm^₂), NO_3^--N removal rate (83.33 mg NO_3^--N L/h) and average coulomb efficiency (32.02%) of Cu₂O/rGO-MFC were higher than those of Pt/C-MFC (485.33 mV, 16.98 mW/cm^₂, 7.38%, 41.67 mg NO_3^--N L/h). Cu₂O/rGO composite material enhance the activity of key enzymes and the content of protein-like components in denitrification of MFC cathode, improving the performance of electricity generation and nitrogen removal of Cu₂O/rGO-MFC.