NOVELTY - The multi-circulation anaerobic reactor comprises an anaerobic reactor body (1) and a multi-layer triangle mud separator (4) arranged in a middle part of an inner cavity of the anaerobic reactor body. The triangle mud separator is provided for dividing an inner cavity into an upper part of a sediment separating area (3) and a lower part of an efficient reaction area (2). A water distributing device is arranged in the reaction area near a bottom part of the reactor body. A water collecting device (6) is arranged in the separating area. A motor is arranged on a top part of the reactor body.    USE - The multi-circulation anaerobic reactor is useful for removing slag.    ADVANTAGE - The multi-circulation anaerobic reactor is capable of automatically removing the slag with high efficiency, and is convenient to observe flow of bio-gas in the efficient reaction area.    DETAILED DESCRIPTION - The multi-circulation anaerobic reactor comprises an anaerobic reactor body (1), a multi-layer triangle mud separator (4) arranged in a middle part of an inner cavity of the anaerobic reactor body. The triangle mud separator is provided for dividing an inner cavity into an upper part of sediment separating area (3) and a lower part of efficient reaction area (2). A water distributing device is arranged in the reaction area near a bottom part of the reactor body. A water collecting device (6) is arranged in the separating area. A motor is arranged on a top part of the reactor body. A main shaft of the motor is stretched into the separating area. A center rotation type, a perimeter rotation type or a traveling crane type slag scraper is mounted on an end of the main shaft and horizontally arranged in liquid level position of the separating area. A slag collecting tank is arranged on an inner wall side of the reactor body corresponding to the slag scraper. A scraper motor is mounted on an inner side of a gas collecting cover provided with a main gas outlet. A water seal tank is arranged on an edge of the gas collecting cover. A gas outlet is arranged on a side wall of the reactor body arranged on the triangle mud separator arranged in a part of 1/2-2/3 of the bottom part of the reactor body. The gas outlet is connected with an external liquid separating device for separating methane and water via a gas exhausting pipe. The liquid separating device comprises a liquid separator connected with a gas exhausting pipe. A secondary gas outlet is arranged on an upper part of a liquid separator connected with a circulating device via a liquid returning pipe. The circulating device is connected with the reaction area via a circulating pipe. A transparent viewing opening is arranged on the liquid separator. Upper and lower parts of the circulating pipe are connected with upper and lower parts of the reaction area.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a multi-circulation anaerobic reactor.    Anaerobic reactor body (1)    Reaction area (2)    Sediment separating area (3)    Mud separator (4)    Water collecting device. (6)