To improve the biogasification of corn stover (CS) for high-efficiency anaerobic digestion, the single alkaline pretreatment and the combined alkaline pretreatment of KOH and Ca(OH)(2) were carried out. The results showed that the effect of KOH pretreatment was much better than Ca(OH)(2) pretreatment, while the combination of 0.5% KOH and 2.0% Ca(OH)(2) was comparable to the effect of 2.0% KOH pretreatment, achieving a cumulative methane yield of 271.38 mL g(vs)(-1), which was 77.01% higher than untreated CS. Considering that Ca(OH)(2) is much cheaper than KOH, it was feasible to use 2.0% Ca(OH)(2) to reduce KOH to 0.5% and achieve similar results. Besides, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses gave evidence for morphology and composition changes of CS after pretreatment. The results collectively indicated that combined alkaline pretreatment could reduce the KOH dose, achieve similar pretreatment effects, and might be a promising method to pretreat agricultural wastes for efficient anaerobic digestion (AD) in future industrial applications.