NOVELTY - A marsh gas generation device comprises down flow anaerobic filter (1), up flow anaerobic fermentation tank (5), and liquor transmission pipe (10); where discharge opening valve (16), liquor transmission pump (12), and feeding opening valve (9) are orderly mounted on the liquor transmission pipe (10); the device further comprises circulating reversing pipe (3), feed back opening valve (2), feeding opening (11), fermentation tank discharge reversing pipe (17), upper discharge opening valve (4), lower discharge opening valve (6), and total valve (13).    USE - The marsh gas generation device is useful for producing methane.    ADVANTAGE - The device has simple structure, quick anaerobic fermentation speed, high gas-generating speed, complete liquor fermentation, and convenient operation.    DETAILED DESCRIPTION - A marsh gas generation device comprises down flow anaerobic filter (1) and up flow anaerobic fermentation tank (5) where liquor transmission pipe (10) is mounted between the discharge opening at the lower part of down flow anaerobic filter (1) and feeding opening at the lower part of up flow anaerobic fermentation tank (5); discharge opening valve (16), liquor transmission pump (12), and feeding opening valve (9) are orderly mounted on the liquor transmission pipe (10), the discharge opening valve (16) is located at one side of down flow anaerobic filter (1), the feeding opening valve (9) is located at one side of up flow anaerobic fermentation tank (5), the upper, lower ends of circulating reversing pipe (3) are respectively connected to feed back opening at the upper part of down flow anaerobic filter (1) and liquor transmission pipe (10), the connection point of the lower end of circulating reversing pipe (3) and liquor transmission pipe (10) is located between the liquor transmission pump (12) and feeding opening valve (9), the feed back opening valve (2) and the feeding opening (11) of circulating reversing pipe are respectively mounted at the tail end of upper end and lower end of the circulating reversing pipe (3), the end head at upper, lower sides of fermentation tank discharge reversing pipe (17) are respectively connected to upper discharge opening, lower discharge opening of the up flow anaerobic fermentation tank (5), the bottom end head of fermentation tank discharge reversing pipe (17) is connected to liquor transmission pipe (10) between the discharge opening valve (16) and liquor transmission pump (12), the upper discharge opening valve (4), lower discharge opening valve (6), and total valve (13) of the fermentation tank discharge reversing pipe are respectively mounted at the upper end, lower end, and bottom end of the fermentation tank discharge reversing pipe (17).    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the marsh gas generation device.    Down flow anaerobic filter (1)    Feed back opening valve (2)    Circulating reverse pipe (3)    Upper discharge opening valve (4)    Up flow anaerobic fermentation tank (5)    Lower discharge opening valve (6)    Feeding opening valve (9)    Liquor transmission pipe (10)