NOVELTY - Ultra-large type straw methane generating pit comprises a fermenting tank (2) and feeding and discharging device. The fermenting tank is installed in a water channel. A top part of the fermenting tank is installed with a flooding mounting plate (6) with small holes. The flooding mounting plate is connected with a bio-gas slurry pipe (3) connected with a circulating pump (8). A top part of the flooding mounting plate and the fermenting tank are installed with a gas collecting hood.    USE - Used as an ultra-large type straw methane generating pit.    ADVANTAGE - The ultra-large type straw methane generating pit is simple and cost-effective, and has improved discharging speed.    DETAILED DESCRIPTION - Ultra-large type straw methane generating pit comprises a fermenting tank (2) and a feeding and discharging device. The fermenting tank is installed in a water channel. A top part of the fermenting tank is installed with a flooding mounting plate (6) with small holes. The flooding mounting plate is connected with a bio-gas slurry pipe (3) connected with a circulating pump (8). A top part of the flooding mounting plate and the fermenting tank are installed with a gas collecting hood. A bottom part of the gas collecting hood is connected with a negative-pressure collecting gas and storing device installed outside of the fermenting tank. The fermenting tank is separated into fermenting tanks. The separated fermenting tanks are connected or separated with each other. The flooding mounting plate is a double-layer hole-containing structure. The feeding and discharging device comprises a guide rail (10) installed above the opening of the methane-generating pit. The guide rail is installed with a feeding and discharging crane installed with a taking material claw and a controller connected with a steel wire rope. The controller is provided for controlling movement of the crane and the lift and opening or closing state of taking material claw. The gas collecting hood is double-layer gas collecting hood. The guide rail is installed with a gas collecting hood roller.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an ultra-large type straw methane generating pit.    Fermentation tank (2)    Biogas slurry area (3)    Flooding mounting plate (6)    Circulating pump (8)    Guide rail. (10)