TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The method above comprises mixing the biogas slurry extracted by the anaerobic digestion phase with the solid matter in the material in step (a) according to the ratio of the 20-40% of the acidification phase volume, using as the feeding material of the acidification phase reactor. In step (b), the acidification phase reactor uses the completely mixing stirring anaerobic fermentation reaction device, controlling the reaction temperature at 35 plus minus 1 degrees C, the organic loading of the acidification phase start being not more than 20 gvs/l, conducting 3-5 days of batch reaction, keeping the pH value of the system being 4.5-5.5, starting orderly batch feeding, the organic loading of the original volume being not more than 10 gvs/l/day, the hydraulic retention time (HRT) being 3-5 days, continuously lifting the organic loading of the volume according to the OLR being 10-18 gvs/l/day. In step (c), the methane production phase reactor uses the anaerobic sludge bed reaction device, controlling the reaction temperature at 35 plus minus 1 degrees C, when starting the methane production phase, adding anaerobic digestion strain according to the effective volume set by the reactor, using as the methanogens source, the strain adapting 3 days under the actual running temperature, solely using the juice of the material to acclimate, setting the original feeding loading at 0.5-1.0 gvs/l/day, keeping the pH value of the system at 7.2-7.6 after 2-3 weeks, starting the acidification phase discharging material, using the acidification phase discharging material and the juice in step (a) as the methane production phase feeding material, continuously lifting the organic loading of the volume according to the OLR being 1-5.5 gvs/l/day, gradually shortening the hydraulic retention time HRT from 30-10 days. In step (a), the juice total volume b in the biomass material, the acidification phase of the solid matter generated in step (b) being volume a, the volume ratio of the acidification phase and the juice in the methane production phase of step (3) is a:b. In step (b), the OLR is equal to 10-18 gvs/l/day, the HRT is 4 days, continuously lifting the organic loading capacity. In step (c), continuously lifting the organic loading capacity according to the OLR is equal to 1-5 gvs/l/day, HRT is 20 days; 5.5 gvs/l/day, HRT is 10 days.