NOVELTY - Device comprises a reaction tank body (1), a water inlet area (2), an active sludge bed (3), a reaction area (4), a gas collecting head (5) and a water discharging pipe. The reaction tank body has its upper end opened and a cavity inside. A water inlet area interconnected with the cavity is arranged at the bottom part of reaction tank body. A gas collecting head is equipped at the internal side of the opening end of the tank body. A water discharging pipe with opening facing upwards interconnected with the cavity by the opening end of tank body, is arranged on the side wall of tank body.    USE - The device is used for the large-scale production of biochemical natural gas.    ADVANTAGE - The device has a simple structure.    DETAILED DESCRIPTION - Device comprises a reaction tank body, water inlet area, active sludge bed, reaction area, gas collecting head and water discharging pipe. The reaction tank body has its upper end opened and a cavity inside. A water inlet area interconnected with the cavity is arranged at the bottom part of the reaction tank body. A gas collecting head is equipped at the internal side of the opening end of the reaction tank body. A water discharging pipe with opening facing upwards which is interconnected with the cavity by the opening end of the reaction tank body is arranged on the side wall of the reaction tank body. The inside of the reaction tank body is mounted with a reaction area and an active sludge bed in an order from the top to the bottom. An INDEPENDENT CLAIM is also included for the industrial large-scale production of biochemical natural gas with organic waste water, comprising: (a) injecting industrial waste water inside the reaction tank body and mixing with flocculent particle sludge of active sludge bed sufficiently; (b) raising the industrial waste water to the reaction area together with the flocculent particle sludge for methane reaction to produce methane and digestion liquid, in which the methane is separated out from the gas collecting head, while the digestion liquid form the water sealing at the gap between the gas collecting head and reaction tank body, discharging excessive digestion liquid by the water discharging pipe; (c) precipitating the flocculent particle sludge in the precipitating area after the reaction and continuously reacting with methane.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the device for the large-scale production of biochemical natural gas.    Reaction tank body (1)    Water inlet area (2)    Active sludge bed (3)    Active sludge bed (4)    Gas collecting head (5)