Corn stover was pretreated using the dry dilute sulfuric acid pretreatment in a helical stirring reactor as described by [9] and [10]. Briefly, the corn stover was presoaked with dilute sulfuric acid (5.0%, w/w) at a solid/liquid ratio of 2:1 for 12 h (the moisture content of the impregnated corn stover was about 33.33%). Then the materials were put into the pretreatment reactor and the hot steam was jetted into the reactor heating the corn stover to 185 °C for 3 min (heating time from 0 to 185 °C was kept within 3–6 min). After that, the pressure was released within 10–30 s and the pretreated corn stover was discharged from the reactor. The reactor was operated at 50 rpm during the pretreatment process. The harvested pretreated corn stover contained about 50% solids materials and was stored at 4 °C before enzymatic hydrolysis.