The invention relates to a biofilm-process multi-cathode chamber denitrifying phosphorus removal and electricity production device, belonging to the technical field of sewage treatment. The biofilm-process multi-cathode chamber denitrifying phosphorus removal and electricity production device comprises an anaerobic tank, a primary settling tank, an aerobic tank, an anoxic pond and an end sedimentation tank which are sequentially connected, wherein the anaerobic tank is taken as an anode chamber of a microbial fuel cell; the aerobic tank, the anoxic pond and the end sedimentation tank are taken as cathode chambers of the microbial fuel cell and are arranged around the anaerobic tank; the anode chamber and the cathode chambers are respectively and externally connected with a resistor; the three walls of the anaerobic tank are respectively provided with a proton exchange membrane; the anaerobic tank is separated from the aerobic tank, the anoxic pond and the end sedimentation tank respectively by the proton exchange membrane; the proton exchange membranes can be freely closed by means of baffle plates. The primary settling tank is connected with the anoxic pond by means of a transcendental sludge pipeline; a biofilm-process nitration technology is adopted by the aerobic tank; the end sedimentation tank is connected with the anaerobic tank by means of a return sludge pipeline; the end sedimentation tank is also provided with a water outlet pipeline and a sludge discharge hole; electricity can be produced during sewage treatment. The biofilm-process multi-cathode chamber denitrifying phosphorus removal and electricity production device effectively reduces the concentrations of chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN) in water, so that an electron acceptor is more widely utilized to produce a stable voltage value.