Bacteriorhodopsin is a kind of biomembrane protein molecule which can store and convert photoenergy. On light illumination, it generates a rapid charge separation and protein electric response signals, which differs from that of the common inorganic photoelectric material. Through electrophoresis method, oriented bacteriorhodopsin films are deposited on ITO conductive glass, with which and a copper electrode, a photodetector with bacteriorhodopsin films and conductive gel sandwiched is constructed. The photodetector′s response to 532 nm wavelength, 30 ps ultrashort laser pulse is studied experimentally. The mechanism of the photodetector′s photoelectric response is theoretically analyzed.