NOVELTY - Biomass energy generation involves poly-culturing and salvaging hyacinth or water lettuce, and crushing the salvaged hyacinth and water lettuce. Lactobacillus seed liquid is added to the mixture in a volume ratio of 0.05%, where the number of Lactobacillus in the seed liquid is 2x 108 colony forming units per ml (CFU/ml). Molasses containing 0.05 wt.% of dry matter are added to the seed liquid and is acidified to acidify hyacinth and water lettuce till the pH value below 4.5 in 2-3 days. Solid is separated from liquid by a spiral extruding machine.    USE - Method for generating biomass energy (claimed).    ADVANTAGE - The biomass energy generation greatly improves organic load of reactor, shortens the detention time to 3 days from 15 days, improves volume gas production rate to be greater than 0.8 biogas per cubic meter from 0.3 biogas per cubic meter, and increases the investment efficiency by over 30%.    DETAILED DESCRIPTION - Biomass energy generation involves poly-culturing and salvaging hyacinth or water lettuce, and crushing the salvaged hyacinth and water lettuce. Lactobacillus seed liquid is added to the mixture in a volume ratio of 0.05%, where the number of Lactobacillus in the seed liquid is 2x 108 colony forming units per ml (CFU/ml). Molasses containing 0.05 wt.% of dry matter are added to the seed liquid and is acidified to acidify hyacinth and water lettuce till the pH value below 4.5 in 2-3 days. Solid is separated from liquid by a spiral extruding machine and the extruding liquor obtained by solid-liquid separation is returned to the acidification tank. The extruding liquor is fermented and the chemical oxygen demand (COD) concentration is maintained at 15000-20000 mg per l in the extruding liquor. The rest of extruding liquor is subjected to anaerobic fermentation in 1000 cubic meter of continuous stirred tank reactor (CSTR) anaerobic digestion tank to generate marsh gas, where the hydraulic detention time is 72 hours. The obtained marsh liquid from the anaerobic fermentation is used as fertilizer and the extruding slag is fermented. 650 tons of extruding slag is put in a cement pit and the top of pit is enclosed by soft plastic and 20 vol.% of marsh slag is inoculated. Anaerobic fermentation is performed for 20-30 days to generate marsh gas, and after fermentation, the residue is transferred to a composting plant for composting for 30 days at 65 degrees C aerobically, which is air-dried and used as organic fertilizer.