NOVELTY - Microcrystalline cellulose is pre-processed and hydrolyzed by (1) preparing organic electrolyte solution (I); (2) pre-treating the microcrystalline cellulose by dissolving in the organic electrolyte solution (I), heating and uniformly mixing to obtain clear and transparent cellulose solution, adding with 5 times by volume of precipitating agent, vibrating, and filtering to obtain filtrate and regenerated cellulose; (3) hydrolyzing the regenerated cellulose; and (4) recovering and recycling the organic electrolyte solution from the filtrate obtained in step (2).    USE - Method for pre-processing and hydrolyzing microcrystalline cellulose used in, e.g. biomass energy production.    ADVANTAGE - The method can quickly dissolve microcrystalline cellulose in the organic electrolyte solution, and is capable of recycling the organic electrolyte solution after the pre-treatment process. It is economical and efficient with less pollution to environment. The initial hydrolysis rate of the pre-treated cellulose can be increased by 5-6 times that of the untreated cellulose, and the 72-hour hydrolysis rate can be increased by 6-8 times.    DETAILED DESCRIPTION - Microcrystalline cellulose is pre-processed and hydrolyzed by (1) preparing organic electrolyte solution (I); (2) pre-treating the microcrystalline cellulose by dissolving in the organic electrolyte solution (I), heating and uniformly mixing to obtain clear and transparent cellulose solution, adding with 5 times by volume of precipitating agent, vibrating, and filtering to obtain filtrate and regenerated cellulose; (3) hydrolyzing the regenerated cellulose; and (4) recovering and recycling the organic electrolyte solution from the filtrate obtained in step (2). Step (1) is performed by uniformly mixing an organic solvent (A) and an ionic liquid (B) at a volume ratio of 1:(1-2) for 36 hours at 90 degrees C under vacuum condition and mechanical vibration to obtain the organic electrolyte solution (I). The organic solvent (A) consists of 1,3-dimethyl-2-imidazolidinone (DMI), pyrrolidinone (preferably polyvinylpyrrolidone) and sulfone (preferably sulfolane) at 1:1:1, 1:2:2 or 1:3:2 mole ratio. The ionic liquid (B) consists of 1-butyl-3-methylimidazolium chloride ((BMIM)Cl) and 1,3-dimethylimidazolium diethylphosphate ((MMIM)DEP) at 1:2 or 1:3 mole ratio. In step (2), the microcrystalline cellulose is added at 5 wt.% in the organic electrolyte solution (I); the heating process can be performed via oil bath heating at 110 degrees C for 30 minutes, or microwave heating at an alpha -radiation energy density of not greater than 50 J/mg; the mixing process can be performed via magnetic stirring at 100 revolutions/minute (rpm) or via ultrasonic oscillation at 300 W and 40 kHz; and the precipitating agent, which is utilized at normal temperature (0-30 degrees C), consists of pure water or may further contain 10 vol.% of ethanol, glycerol or polyethylene glycol (PEG-400). Step (3) is performed by adding the regenerated cellulose in hot water at 60 degrees C to wash for 3 times; freeze-drying to obtain cellulose powder; and hydrolyzing in sodium citrate buffer solution system added with 60 FPU/g cellulase and 64 pNPGU/g cellobiase. The sodium citrate buffer solution has a concentration of 50 mM and a pH of 4.8. Step (4) is performed by (a) subjecting the filtrate obtained in step (2) into vacuum distillation at 0.03 MPa and 90 degrees C for 20-30 minutes to obtain distillate and residual fraction, subjecting the distillate into vacuum distillation at 0.03 MPa and 30 degrees C for 10-20 minutes to recover the organic solvent; (b) evaporating the residual fraction at 90-100 degrees c, vacuum drying for 24 hours to recover the ionic liquid; and (c) recycling the recovered organic solvent and ionic liquid to prepare regenerated organic electrolyte solution in step (1).