Enzymatic hydrolysis of corn stover was performed in an integrated membrane bioreactor (MBR) incorporating a 10 kDa flat sheet polysulfone membrane to increase cellulose conversion and to reduce enzyme dosage. Several pretreatment methods and semi-continuous MBR were examined to investigate their effect on the glucose yield and enzyme utilization efficiency. Compared with conventional batch reactor (CBR), cellulose conversion increased by 5% in a MBR because of the removal of glucose and cellobiose inhibitors. More than 15% increment in cellulose conversion was obtained using fed-MBR, and the reaction rate improved significantly. Enzyme utilization efficiency in a fed-batch MBR were 1.94-fold of CBR and 1.34-fold of fed-CBR for corn stover pretreated by soaking in aqueous ammonia and 3.31-fold of CBR and 1.32-fold of fed-CBR for corn stover pretreated by diluted sulfuric acid-sodium hydroxide.