In this research, the effects of combined severity parameters (CS?), response surface methodology (RSM), and separation factor (SF) on the recovery and/or removal rate of main fraction for acid-catalyzed hydrolysis of corn stalk were defined and investigated. The results demonstrated that the maximum total sugar yield (44.31 wt%) was obtained from corn stalk after hydrolysis with 2.05 wt% of acid catalysis at 113.17 degrees C for 61.69 min (CSP0 = 1.80) while the high glucan recovery (88.02%), de-pentosane rate (97.21%), and SF of solid phase fraction were obtained with CSP0 range of 1.14-2.18 (CSP1 range of 1.80-2.82). The findings suggest that CSP1 can be used to more efficiently evaluate the separation degree of glucan with lignin (SFG-L) than CSP0. The acid-catalyzed hydrolysis of corn stalk has an advantage of high solid liquid phase recovery and CSP can be used to describe the effect of acid hydrolysis. (C) 2015 Elsevier Ltd. All rights reserved.