NOVELTY - An energy-saving efficient methane fermentation warming system in northern cold area, comprises a batching pond (9), a first liquid transfer pump (8), an acidification tank (7), a second liquid transfer pump (6), a methane generating tank (3), and a third liquid transfer pump (2) serially connected in turn; where a hot water input pipe (1) is connected on the batching pond (9); the heat exchanger (5) is arranged between the acidification tank (7) and the methane generating tank (3); and the inlet of the heat exchanger (5) is connected with the outlet of the second liquid transfer pump (6).    USE - The energy-saving efficient methane fermentation warming system is useful in northern cold area (claimed).    ADVANTAGE - The energy-saving efficient methane fermentation warming system has simple and rational structure, convenient and simple operation, reliable working, convenience for maintenance, high methane generation efficiency, and good energy-saving effect.    DETAILED DESCRIPTION - An energy-saving efficient methane fermentation warming system in northern cold area, comprises a batching pond (9), a first liquid transfer pump (8), an acidification tank (7), a second liquid transfer pump (6), a methane generating tank (3), and a third liquid transfer pump (2) serially connected in turn; where a hot water input pipe (1) is connected on the batching pond (9); the heat exchanger (5) is arranged between the acidification tank (7) and the methane generating tank (3); the inlet of the heat exchanger (5) is connected with the outlet of the second liquid transfer pump (6); the outlet of the heat exchanger (5) is connected with the inlet of the methane generating tank (3); and two ends of the liquid circulating pipe (4) are separately connected with inlet of the heat exchanger (5) and the outlet of the third liquid transfer pump (2).    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the energy-saving efficient methane fermentation warming system in northern cold area.    Hot water input pipe (1)    Third liquid transfer pump (2)    Methane generating tank (3)    Liquid circulating pipe (4)    Heat exchanger (5)    Second liquid transfer pump (6)    Acidification tank (7)    First liquid transfer pump (8)    Batching pond (9)