Abstract: Various combined processes of steam explosion and alkaline pretreatment were experimentally compared and evaluated on wheat straw materials. The morphological characterizations of pretreated wheat straw were performed by scanning electron microscope and FT-IR spectroscopy, to qualitatively determine the composition changes of pretreated wheat straw. Comparing to the single process or the combination of alkaline pretreatment followed by steam explosion(ASP), the steam explosion followed by alkaline process(SAP) pretreatment removed most of lignin, degraded hemicelluloses, and incurred a higher surface area of the cellulose-rich substrates. And the remaining contents of cellulose, xylan and lignin in SAP sample were 88.15%, 5.55%, 4.13%, respectively. Moreover, SAP enhanced the fed batch enzymatic hydrolysis of cellulose-rich substrates to a maximum value of 80.53% even at the high cellulose loading of 18%. The results indicated that the SAP process is advantageous scheme for the enhancement of enzymatic efficiency.