NOVELTY - The modularized anaerobic reactor comprises a reactor shell (1) having a body, a direct current cleaning port (10), a temperature sensor, a drain pipe (2), a methane pipe (3), an overflow pipe (6), a heating device, and a hydraulic circulating stirring device. The reactor shell: comprises a bottom; is designed as a horizontal tank and made of steel. The stirring device comprises a hydraulic circulating pipe, a raw material feeding pipe, and a mixing pipe. The mixing pipe penetrates the bottom of the shell, and extends to the shell in an upper part of the feeding pipe.    USE - The modularized anaerobic reactor is useful for producing marsh gas such as methane.    ADVANTAGE - The modularized anaerobic reactor can be simply and efficiently manufactured with reduced size.    DETAILED DESCRIPTION - The modularized anaerobic reactor comprises a reactor shell (1) having a body, a direct current cleaning port (10), a temperature sensor, a drain pipe (2), a methane pipe (3), an overflow pipe (6), a heating device, and a hydraulic circulating stirring device. The reactor shell: comprises a bottom; is designed as a horizontal tank and made of steel. The stirring device comprises a hydraulic circulating pipe, a raw material feeding pipe, and a mixing pipe. The mixing pipe penetrates the bottom of the shell, and extends to the shell in an upper part of the feeding pipe that is located at the bottom of the shell body. A feeding pipe outer circulation pump is connected with an input port and an output port. The heating device comprises a water supply pipe, a water return pipe and a heat exchanger (9). The heat exchanger is horizontally located at the reactor shell. The water supply pipe and the water return pipe are located at the bottom of the reactor shell body, and are connected with the heat exchanger, which is connected with a water inlet and a water outlet. The drain pipe, the methane pipe, the overflow pipe, the hydraulic circulating stirring device and the heating device are installed at the bottom of the reactor shell. The volume of the anaerobic reactor is 60 m3.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an anaerobic reactor.    Reactor shell (1)    Drain pipe (2)    Methane pipe (3)    Overflow pipe (6)    Heat exchanger (9)    Cleaning port. (10)