NOVELTY - Pre-processing butanol, comprises (i) cutting bagasse, drying, and mechanically crushing; (ii) performing liquid water treatment; (iii) performing microwave treatment; (iv) performing microbial decomposition; (v) washing solid residue III with double-distilled water, drying, and mixing solid residue III with aqueous ammonia; (vi) performing enzymatic hydrolysis with enzymatic hydrolysis mixture include dried solid residue IV and cellulose, reacting, and collecting filtrate V and solid residue V; and (vii) performing solid state fermentation (SSF), or separate hydrolysis and fermentation (SHF).    USE - The method is useful for pre-processing butanol (claimed).    ADVANTAGE - The method does not require to carry out detoxification purification process of pre-processing decomposing product; performs direct biological fermentation process of butanol; produces product with controllable inhibitors; is economical, and environmental friendly; and has high yield.    DETAILED DESCRIPTION - Pre-processing butanol, comprises (i) cutting bagasse into a length of 5-10 cm, drying for 2 days at 65 plus minus 2 degrees C, and mechanically crushing by placing bagasse, and passing through 20 mesh sieve, to obtain bagasse slag powder having small particle diameter of less than 830 mu m; (ii) carrying out liquid water treatment by soaking the resulting material of the step (i) in water in a solid-liquid mass volume ratio of 250 g/l for 12 hours at room temperature, and pre-heating under steam for 45 seconds, adding liquid hot water at 200 plus minus 3 degrees C, and then reacting for 1 hour, filtering, and collecting the filtrate I and solid residue I; (iii) carrying out microwave treatment by adjusting the resulting solid residue of the step (ii) under humidity of 40%, placing the material into a reactor, introducing nitrogen by taking out oxygen, and then placing the reactor into microwave pyrolysis furnace at 4 degrees C for 8-12 hours, reacting for 7 minutes at less than 120 degrees C, and cooling the material to room temperature, and soaking the resultant reaction solution in 90% ethanol, filtering, and collecting filtrate II and solid residue II; (iv) carrying out microbial decomposition by drying the resulting solid residue II, adding into a culture solution, mixing, sterilizing at 121 degrees C, adjusting humidity at 30%, adding 10 wt.% bacteria decomposing bacteria, fermenting at 30 degrees C for 10 days, filtering, and collecting filtrate III and solid residue III, where the culture solution includes 30 mg boric acid, 20 mg manganese(II) chloride tetrahydrate, 185 mg zinc sulfate heptahydrate, 20 mg sodium molybdate dihydrate , 280 mg ferrous sulfate monohydrate, 200 mg cupric sulfate, 5 g ammonium nitrate, 1 g monopotassium phosphate, 0.15 g magnesium sulfate monohydrate, 0.11 g calcium chloride and 1 l double-distilled water, and has a pH of 7, and the decomposing bacteria is Aspergillus niger ATCC 1015, Trichoderma reesei ATCC 26921 and Penicillium janthinellum ATCC 44750; (v) washing the resulting solid residue III with double-distilled water, and drying, where the solid-liquid mass ratio is 1:2, and mixing solid residue III with aqueous ammonia, under a pressure of 0.1 MPa, and reacting for 30 minutes at 90 degrees C, filtering, and collecting filtrate IV and solid residue IV; (vi) soaking solid residue IV in water for 2 hours, adjusting pH to 7, concentrating, drying, and carrying out enzymatic hydrolysis by using an enzymatic hydrolysis mixture (per 500 ml) includes 50 g dried solid residue IV, 10 g cellulose, 100 ml OPTIMASH BG (RTM: High activity beta 3-glucanase/xylanase mixture), 5 mg chloramphenicol and 2.5 mg kanamycin, and then adjusting the pH of enzymatic hydrolysis mixture to 5, at 55 degrees C, shaking at a speed of 220 rotations/minute, reacting for 60 hours, filtering, and collecting filtrate V and solid residue V; and (vii) mixing filtrate I, filtrate II, filtrate III, filtrate IV and solid residue IV, and subjecting to solid state fermentation (SSF), or mixing filtrate I, filtrate II, filtrate III, filtrate IV and filtrate V, subjecting to rotary evaporation, and separate hydrolysis and fermentation (SHF).