Abstract: The effects of microwaveassisted sulfuric acid and sodium hydroxide pretreatment on sugar yields of enzymatic hydrolysis of corn stover were studied. Four factors, i.e., temperature, acid or alkali concentration, pretreatment time and liquid to solid ratio were selected in the single factor analysis method. It was found that with microwaveassisted sulfuric acid pretreatment the optimal pretreatment conditions were temperature 190℃, sulfuric acid concentration 10 g/L, pretreatment time 3 min and liquid to solid ratio 20. Under these conditions the sugar yields were 44.6% in pretreatment and 30.3% in enzymatic hydrolysis. On the other hand, with microwaveassisted sodium hydroxide pretreatment the optimal conditions were temperature 130℃, sodium hydroxide concentration 15 g/L, pretreatment time 7 min and liquid to solid ratio 30. Under these conditions the sugar yields were 1.5% in pretreatment and 80.0% in enzymatic hydrolysis.