NOVELTY - The biological denitrification device comprises an integral water tank, an anoxic or anaerobic upflow anaerobic sludge blanket (UASB) reactor and a middle water tank. A sequential batch reactor (SBR) is also provided. The anoxic or anaerobic UASB reactor is provided with a circulatory system. The SBR reactor and SBR nitration zone are connected with an SBR nitration liquid return line. The SBR nitration zone is connected with a water inlet at bottom part of the anoxic or anaerobic UASB reactor via percolate water inlet pipe, where the UASB reactor is provided with a three-phase separator.    USE - Biological denitrification device.    ADVANTAGE - The biological denitrification device removes the organic matter and nitrogen from the sewage synchronistically and deeply by using UASB-SBR biochemical system, and also produces methane in anaerobic reaction in a cost-effective manner.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for biological denitrificaion of anoxic or anaerobic UASB-SBR sewage using the device, which involves:    (A) leading UASB percolate water inlet pump and regurgitant SBR nitration liquid supernatant fluid from the integral water tank, controlling volume ratio of the percolate water inlet pump and regurgitant SBR nitration liquid supernatant fluid at 3:1;    (B) using organic matter in the water and denitrifying bacteria and methanogen in the reactor to start the anoxic nitration reaction and anaerobic methane generating reaction and using organic carbon source in the water to reduce nitrite nitrogen (NO2--N) in the SBR nitration liquid supernatant fluid to remove nitrogen, oxidizing the organic matter to methane, water and carbon dioxide by the methanogen in the UASB reactor to remove the organic matter;    (C) leading the outlet water in the UASB reactor to the middle water tank, using ammonium nitrogen (NH4+-N) as electron donor for phototrophic nitrobacteria and oxygen as electron acceptor, oxidizing NH4+-N to nitrite nitrogen to remove ammonia; and    (D) precipitating the resultant for 30-60 minutes and controlling chemical oxygen demand (COD) nitrate nitrogen at 3.5.