Reducing the consumption of cellulase was the key factor to overcome the economic problem in the refining process of lignocellulose. In this study, the enzymatic hydrolysis performance of long fibers and short fibers fractionated by steam explosion classification and the possibility of using steam explosion classification to reduce the consumption of cellulase were investigated. The results showed that the enzymatic hydrolysis difficulty of short fiber was significantly lower than that of long fiber. The enzymatic hydrolysis rate of cellulose in short fiber was 1.62 times that of long fiber after 48 h of enzymatic hydrolysis at the enzyme dosage of 20 FPU/g DM. Under the enzyme dosage of 5 FPU/g DM, the enzymatic hydrolysis rate of cellulose in short fiber was 58.23% after 36 h. Under the enzyme dosage of 20 FPU/g DM, the enzymatic hydrolysis rate of cellulose in long fiber was only 51.54% after 36 h. The consumption of cellulase was reduced by 75%. The difference in enzymatic hydrolysis difficulty was due to the fact that long fiber and short fiber came from different tissues of corn straw. Due to the difference in mechanical strength, the tearing effect generated by the steam explosion crushed the husk and core into diverse particle sizes. The variety of volumes and shapes provided the basis for classification. Short fibers were mainly composed of parenchyma cells from the core, while long fibers were mainly composed of fiber cells from the husk. The crystallinity of cellulose in short fiber was lower, so the enzymatic hydrolysis difficulty was lower than that of long fiber. In addition, during the enzymatic hydrolysis of short fiber, the release of bound water was more sufficient. The liquefaction time of short fiber was shorter than that of long fiber. This indicated that mass transfer efficiency was improved during the enzymatic hydrolysis of short fiber, which was conducive to reducing the negative effect of product inhibition on enzyme activity and improving the enzymatic hydrolysis efficiency. This study provided an effective method for improving the homogeneity of lignocellulosic materials. The steam explosion classification technology effectively changed the difficulty of enzymatic hydrolysis of corn straw and saved the cost of cellulase. This was of great significance to the exploitation of lignocellulosic resources.