Abstract: In the research fields of lignocellulosic materials, their high-concentration reducing sugars production is an important foundation for their energy conversion. Based on Box-Behnken design, maintenance pressure time, steam pressure and ammonium acid carbonate concentration were chosen as the three important factors with three levels. The process conditions of corn stalk steam explosion pretreatment were optimized by response surface methodology, and a mathematical model of a second order quadratic equation was developed for reducing sugar concentration. The results showed that the optimized technological parameters were as follows：maintenance pressure time 227 s, steam pressure 3.08 MPa, ammonium acid carbonate concentration2.11%. Corn stalk steam explosion pretreatment was saccharified under these conditions for 48h, its reducing sugar concentration was up to 60.04 g/L, and saccharification rate reached 83.7% of its theoretical value(71.7%). The results verified the validity of the mathematical model. This study demonstrates that steam explosion pretreatment can significantly improve reducing sugar concentration .