NOVELTY - Shifting, cutting and stirring method comprises adding fermentation raw material inside biogas fermentation system, fermenting, producing biogas, collecting biogas inside a gas storage plate of each fermentation area, pushing pneumatic piston upward movement, driving through pneumatic piston, stirring biogas slurry, Shifting, dislocating, cutting, stirring biogas slurry, reducing pressure inside gas storage plate, using gravity for balancing weight block which is set on top of pneumatic piston, prompting pneumatic piston to return and disturbing biogas slurry.    USE - Used as shifting, cutting and stirring method.    DETAILED DESCRIPTION - Shifting, cutting and stirring method comprises adding fermentation raw material inside biogas fermentation system, fermenting, producing biogas, collecting biogas inside a gas storage plate of each fermentation area, where the adjacent fermentation area of biogas pressure is the same, pushing pneumatic piston upward movement which is set with top gas plat of fermentation area, driving through pneumatic piston which is provided at the bottom of the piston, drawing stirring device upward movement, stirring biogas slurry, when the adjacent fermentation area of gas pressure is not the same, the adjacent fermentation area of pneumatic piston trajectories are not synchronized, setting adjacent pneumatic piston bottom the first drawing block and the second drawing block, shifting, where the first drawing block and second drawing block is set in sidewall of stirring blade, dislocating, cutting, stirring biogas slurry, where the gas storage plate is set with airway to external output of biogas, reducing pressure inside gas storage plate, using gravity for balancing weight block which is set on top of pneumatic piston, prompting the pneumatic piston to return and disturbing biogas slurry. An INDEPENDENT CLAIM is also included for biogas fermentation system used in shifting, cutting and stirring method, comprising fermentation tank body, hydraulic pressure room. The fermentation tank body is set with fermentation chamber, the fermentation tank body is set with fermentation chamber corresponding to the left and right side wall, the fermentation chamber is connected with feedstock port and discharge port, the fermentation tank on the side wall of the body is provided with supporting device. The gas storage plate is placed in the fermentation tank body and fixed to the supporting device. The gas storage plate is surrounded with top sealing and opening at lower end. The gas storage plate close to the feedstock port end of the sidewall is feedstock port air resistance plate and the gas storage plate close discharge port of one end of the side wall is gas discharge port blocking plate. The gas storage plate and fermentation tank of fermentation chamber is adapted to the shape and gas storage plate width less than fermentation tank body of fermentation chamber of width. The hydraulic pressure room is fixed to gas storage plate. The one end side of hydraulic pressure room close to feedstock port is provided feedstock port drain pipe. The one end side of hydraulic pressure room close to discharge port is provided discharge port drain pipe. The fermentation system further comprises rod. The rod is made by cross rod and vertical rod. The one end side of crossbar is connected vertically to vertical rod. The top part of vertical rod is provided two vertical bars, which are located between holding rod. The rod is placed in the fermentation chamber and two vertical rod are located between the gap in gas storage plate and fermentation tank body.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the biogas fermentation system.