The corn stalks were pretreated by continuous screw extrusion steam explosion. The effects of the concentration of acid, reaction time, reaction temperature and the ratio of feedstuff to dilute acid on the conversion of the pretreated corn stalks to reducing sugars were investigated. In the orthogonal experiment of sulfuric acid hydrolysis, the effect order of five factors arranged from large to small was the type of raw materials, the ratio of feedstuff to dilute acid, hydrolysis temperature, concentration of H2SO4, and reaction time. The materials exploded at 120℃ for 10 min had the highest reducing sugar yield at the optimal conditions of 3% sulfuric acid concentration, hydrolysis temperature 110℃, hydrolysis time 60 min, and ratio of feedstuff to dilute acid of 1:20, and the yield of reducing sugars was 39.7%. In the orthogonal experiment of hydrochloric acid hydrolysis, the effect order of five factors was hydrolysis temperature, the type of raw materials, hydrolysis time, concentration of acid and the ratio of feedstuff to dilute acid. The optimal conditions were 3% HCl, hydrolysis temperature 110℃, hydrolysis time 60 min, ratio of feedstuff to dilute acid of 1:20 and the material explosion at 120℃ for six minutes, and the yield of reducing sugars was 42.0%.