Abstract: Abstract: Corn straw is one of the most abundant agricultural and forest residues containing cellulose, hemicellulose, and lignin. About 2.24×108 tons of corn straw are produced per year in china, most of which is burned or lost in farmland, and only a small part is used as feed for livestock. Because corn straw is abundant in cellulose, it can be used as a substitute for grain to produce fuel-ethanol, which can be a significant contribution for relieving the crisis of resource and foodstuff shortage. The process of producing fuel-ethanol includes pretreatment, enzymatic hydrolysis, fermentation, and distillation. Cellulose, hemicellulose, and lignin in corn straw form stable polymers, which hardly dissolve in water, dilute acid, dilute alkali, and most organic solutions. Each component interrelates with all the others. Because of the complex configuration, hemicellulose and lignin will hinder the degradation of cellulose. To utilize the cellulose, corn straw must be pretreated. To improve the reduction of sugar yield in corn straw, the hydrolysis method of using extremely low sulfuric acid followed by enzymolysis is employed to treat corn stalk. To investigate the mechanism of reducing sugar conversion in acid hydrolysis and enzymolysis, the yield of totally reduced sugar, glucose and xylose was analyzed with acid hydrolysis followed by enzymolysis under different acid concentrations, temperatures and reaction times. Acid concentrations 0.1%, 160℃, 55 min, 180 r/min, solid-liquid ratio 1:10 was confirmed by orthogonal experiment. Through acid hydrolysis followed by enzymolysis (enzyme 5.0%, pH 4.6, 24 h, 50℃), the yield of totally reduced sugar, glucose, and xylose was 56.22%, 16.97% and 18.83%, respectively. The concentration of totally reduced sugar, glucose, and xylose was 62.46, 18.85 and 20.92 g/L, respectively. After acid hydrolysis and enzymolysis treatment, the corn stalk component was analyzed by infrared spectral and the Van Soest methods. The conversion of cellulose and hemicellulose was 88.52% and 95.18%, respectively. The conversion of totally reduced sugar, glucose, and xylose was 88.11%, 44.86% and 72.49%, respectively. Extremely low acid pretreatment can hydrolyze hemicellulose into monosaccharides and degrade the crystalline structure of cellulose. The pretreated cellulose with high porosity can be hydrolyzed by cellulose efficiently. This method can avoid degradation of monosaccharides, improve reduced sugar yield and increase the conversion efficiency of corn straw cellulose.