Microbial fuel cell(MFC) is a novel environmental friendly energy device which has received great attention due to its technology for producing electricity directly from organic or inorganic matter by using bacteria as catalyst.To date,many experiments have been carried out to achieve the maximum power output with advective flow through porous anode to the cathode in the MFC.However,the precise mechanical mechanism of flow through anode and the quantified relationship between electrode spacing and MFC performance are not yet clearly understood.It has been found experimentally that the power output can be increased apparently at certain electrode spacing configuration.Based on these available experimental data,this paper investigates the effect of spacing between electrodes,the Darcy number of porous anode and the Reynolds number on the power production performance of MFC by using lattice Boltzmann method.The numerical simulation results present that the distance between electrodes significantly influences the flow velocity and residence time of the organic matter attached to the anode in the MFC.Moreover,it is found that the Darcy number of porous anode and the Reynolds number can regulate the output efficiency of MFC.These results perform better understanding of the complex phenomena of MFC and will be helpful to optimize MFC design. Microbial fuel cell (MFC) is a novel environmental friendly energy device which has received great attention due to its technology for producing electricity directly from organic or inorganic matter by using bacteria as catalyst. To date, many experiments have been carried out to achieve the maximum power output with advective flow through porous anode to the cathode in the MFC. However, the precise mechanical mechanism of flow through anode and the quantified relationship between electrode spacing and MFC performance are not designed yet. It has been found experimentally that the power output can be increased apparently at certain electrode spacing configuration. This paper investigates the effect of spacing between electrodes, the Darcy number of porous anode and the Reynolds number on the power production performance of MFC by using lattice Boltzmann method. The numerical simulation results present that the distance between electrodes sign ificantly influences the flow velocity and residence time of the organic matter attached to the anode in the MFC. Moreover, it is found that the Darcy number of porous anode and the Reynolds number can regulate the output efficiency of MFC. These results perform better understanding of the complex phenomena of MFC and will be helpful to optimize MFC design.