NOVELTY - Preparation of acetone-butyl alcohol mixed liquid includes crushing biomass cake with water content of less than 7 wt.%, adding water to ground particles, stacking, watering until water content of 12-17 wt.%, maintaining at 42-48 degrees C, high-temperature fermenting for 12-18 days, introducing fermented coarse particles into fermentation cylinder, directing nitrogen in the base part, adding prepared bacteria solution, continuing directing nitrogen for 30-50 minutes, and regulating pH at 6.5-8. Fermentation is conducted at 30-55 degrees C.    USE - For preparing acetone-butyl alcohol mixed liquid.    ADVANTAGE - The method is safe and easy to control, has low production cost, and does not generate environment pollution. The product belongs to natural resolvable material.    DETAILED DESCRIPTION - Preparation of acetone-butyl alcohol mixed liquid includes crushing biomass cake with water content of less than 7 wt.% (i.e. material compressed and extracted from xylophyta or herbaceous oil plant) into particles having a diameter of 3-5 cm; and adding water to ground particles, stacking in a room to a height of 1.2-1.5 cm and a diameter of 1.6-2.4 cm, watering until water content of 12-17 wt.%, maintaining room at 42-48 degrees C, high-temperature fermenting for 12-18 days, introducing fermented coarse particles into fermentation cylinder via a feeding cylinder, directing nitrogen in the base part to drain air in the cylinder, adding prepared bacteria solution at bacteria solution-fermented particle volume ratio of 1:17-22, continuing directing nitrogen for 30-50 minutes to maintain oxygen-free environment, and regulating pH at 6.5-8. Fermentation is conducted at 30-55 degrees C. The strain in bacteria solution is three strains mutagenized, optimized and screened via acetone-butyl alcohol clostridium. Fermentation broth produced after anaerobic fermentation is the acetone-butyl alcohol mixed liquid. INDEPENDENT CLAIMS are included for:    (1) preparation of hydrogen by spreading active living sludge on hydrogen fermentation tank base as fermentation bacteria source, transferring fermented remainder of acetone-butyl alcohol mixed liquid preparation into hydrogen fermentation tank, maintaining the temperature of fermentation tank at 33-45 degrees C, regulating pH of fermenting material at 4-4.5, and fermenting for 20-24 hours; and    (2) preparation of methane gas by transferring waste produced when fermenting to prepare hydrogen to a fermentation tank, spreading active living sludge containing methane generation bacteria on tank base, conducting refermentation, regulating pH of fermenting material at 5.9-7.2, maintaining the temperature of fermentation tank at 40-55 degrees C.