The system of the photoelectric response of Bacteriorhodopsin membrane (SPRBM) is an important system for molecular-electric research. Based on the Hong’s concept of chemical capacitance, a functional block diagram model of SPRBM was developed. It consists of C-capacitance and its current source; N-capacitance and its current source; proton transfer channel and back channel .By using this model ,a pulse response function and potential distribution of the “Fe/Br/Gel/Cu” photo-cell and its equivalent circuit were derived.