Abstract: Preparation conditions of sugar from corn stalk by alkali pretreatment and enzymatic hydrolysis were investigated. Influence of NaOH pretreatment conditions on the compositional changes, enzyme hydrolysis efficiency and total sugar yield were examined. Test results showed that the NaOH pretreatment had a good effect of lignin removal,but the loss of hemicellulose was difficult to avoid.In order to get a high sugar yield, the strength of pretreatment needed be reduced as appropriate, within the experiments.The pretreatment condition of the maximum overall sugar yield was found to be 1.5 % of NaOH, 80 ℃,1∶10 solid to liquid ratio, and 1 h reaction time. The pretreated corn stalk solid retained 100 %cellulose and 69.58 % hemicellulose, but 54.84 % lignin was removed. The enzymatic digestibility of the cellulose content increased from 24.18 % to 71.29 % with 15 μmol/(min·g) and 30 μmol/(min·g) cellulose enzymes loading, where as the digestibility of hemicellulose content increased to 78.85 %. Under this condition, the overall sugar yield increased form 20.20 % to 66.86 %, compared with untreated corn stover.