NOVELTY - Producing methane by U-type multiple fermentation zones methane generating system comprises feeding fermentation material from a feed tube into a fermentation pipeline for fermenting to produce methane gas, collecting methane gas in the fermentation area between feeding/discharging pipe and adjacent air blocking plate, occupying the space of the fermentation zone, extruding biogas slurry, flowing towards the feeding pipe and discharging pipe, increasing the liquid level of biogas slurry within the feeding pipe and discharging pipe, and storing methane gas in one of the fermentation zones.    USE - The method is useful for producing methane by U-type multiple fermentation zones methane generating system (claimed).    DETAILED DESCRIPTION - Producing methane by U-type multiple fermentation zones methane generating system comprises (a) feeding fermentation material from a feed tube into a fermentation pipeline for fermenting to produce methane gas, collecting methane gas in the fermentation area between feeding/discharging pipe and adjacent air blocking plate or between the adjacent air blocking plates, occupying the space of the fermentation zone, extruding biogas slurry, flowing towards the feeding pipe and discharging pipe, increasing the liquid level of biogas slurry within the feeding pipe and discharging pipe, conveying the biogas in the fermentation pipeline through the feeding pipe into a discharging hole, and flowing into a water pressure chamber through the discharging pipe from the drain hole; and (b) storing methane gas in one of the fermentation zones, dropping the pressure of the methane gas stored in the fermentation zone, then flowing the biogas slurry into the adjacent fermentation zone, feeding the biogas slurry through the feeding pipe into drainage hole and returning into the fermentation pipeline through the drainage pipe to finish the liquid circulation flow, and reducing the methane gas space, where methane gas is produced by fermentation process.