NOVELTY - The reactor has a reactor tank body whose two sides are provided with a water inlet main pipe and a pressure water back port. The water inlet main pipe is connected with a water inlet pipe and U-groove type water distributing branch pipe. The pressure water back port is connected with a reverse flushing water pipe and a U-type water distributing branch pipe. The U-type water distributing branch pipe is connected with a bottom part of the tank body. A middle part of the tank body is provided with a filler bracket. The filler bracket is formed with a filler forming filling layer.    USE - Upflow anaerobic sludge blanket reactor.    ADVANTAGE - The upflow anaerobic sludge blanket reactor has high stability, no mud bed dead angle, can prevent water distribution system blockage, high biological activity and chemical oxygen demand removal rate of 85-90%.    DETAILED DESCRIPTION - The reactor has a reactor tank body whose two sides are provided with a water inlet main pipe and a pressure water back port. The water inlet main pipe is connected with a water inlet pipe and four U-groove type water distributing branch pipes. The pressure water back port is connected with a reverse flushing water pipe and a U-type water distributing branch pipes. Each U-type water distributing branch pipe is connected with a bottom part of the tank body. A middle part of the tank body is provided with a filler bracket. The filler bracket is formed with a filler forming filling layer. An upper part of the tank body is provided with a three-phase separator that is provided with a biogas collecting pipe and a water outlet. An inlet water valve is connected with the water inlet main pipe and the U-groove type water distributing branch pipes. A backflushing valve is connected with the reverse flushing water pipe. Manholes are formed in the lower and middle parts of the tank body. Pressure water back holes are symmetrically formed in the tank body. The water distributing branch pipes are formed with 15-100 water distributing holes. The filler is polypropylene elastic filler having diameter of 150 mm and valid length of 3000 mm.