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The bioconversion technique is one of the important methods for producing environmentally friendly bioenergy from lignocellulosic biomass. The objective of this study is to explore the effect of different mechanochemical combined pretreatments on the enzymatic hydrolysis of corn stalks at room temperature. In this study, corn stalk was used as biomass material, lower load of NaOH with mass fractions 0, 1%, 2%, and 3% was used in the groups of NaOH pretreatment alone, the dry NaOH/ball milling combined pretreatment and the wet NaOH/ball milling combined pretreatment, respectively. The following 72 h enzymatic hydrolysis experiments for different pretreated corn stalks were carried out by using the enzyme CellicCtec2 (Novozymes, Denmark). The particle size, crystallinity, surface micromorphology, lignocellulosic composition, and the functional group changes of the pretreated corn stalk samples were systematically characterized. The effects of the different NaOH/ball milling combined pretreatments on samples’ physicochemical properties on enzymatic hydrolysis yield and their correlations were further investigated and discussed in detail. The results showed that both dry and wet NaOH/ball milling combined pretreatment significantly improved the corn stalk glucose yield compared with NaOH pretreatment (P<0.01). And with the increase of NaOH mass fraction (from 1% to 3%), the glucose yield of corn stalk with dry and wet NaOH/ball milling combined pretreatment increased clear (P<0.01). When the mass fraction of NaOH was 3%, the glucose yield of the dry and wet NaOH/ball milling combined pretreatment reached 71.0% and 73.1%, respectively. The dry NaOH/ball milling combined pretreatment effectively reduced the particle size and crystallinity of the corn stalk, compared with the NaOH pretreatment. Once the NaOH mass fraction was 0, the particle size and crystallinity of the corn stalk treated by the dry NaOH/ball milling were the lowest, 15.8 μm and 25.9%, respectively. But, the particle size and crystallinity of the corn stalk pretreated by the wet NaOH/ball milling were higher than those of the dry NaOH/ball milling combined pretreated samples. The cellulose mass fraction of different combined pretreatment samples gradually increased, with the increase of NaOH mass fraction. There was no significant difference in the cellulose mass fraction between the two pretreatment samples under the same NaOH loading conditions. The cellulose mass fraction was up to 48.5% in the wet NaOH/ball milling combined with pretreated samples, when the NaOH mass fraction was 3%. The lignin mass fraction decreased significantly with the increase of NaOH mass fraction (P<0.01). The lignin mass fraction of corn stalk with the wet NaOH/ball milling combined pretreatment was lower than that of dry ones. Once the NaOH mass fraction was 3%, the lignin mass fraction of the wet NaOH/ball milling combined pretreatment was the lowest at 14.9%. Regardless of the dry and wet NaOH/ball milling combined pretreatment, the enzymatic glucose yields were significantly positively correlated with cellulose mass fraction and average particle size D50 (P<0.01), and significantly negatively correlated with lignin mass fraction (P<0.01). The dry NaOH/ball milling combined pretreatment significantly reduced the crystallinity of the corn stalk, thereby enhancing the yield of enzymatic hydrolysis of the corn stalk to a certain extent (P<0.05). This study provides data support to help further reveal the mechanism of biomass mechanochemical combined pretreatment behind. [ABSTRACT FROM AUTHOR]