Abstract: In this paper,the pressure of 2.0,2.4 MPa and pressure holding time of 30 s,1,2 and 4 min were selected to conduct steam blasting pretreatment on hawthorn pomac,and to explore the influence of different steam blasting pretreatment conditions on components,enzymatic hydrolysis effect and microstructure of hawthorn pomac. The results showed that the steam explosion pretreatment increased the soluble sugar content and decreased the cellulose content of hawthorn pomace. At the same time,the total flavonoid extraction increased with the increase of pretreatment conditions. The pretreatment conditions were 2.4 MPa and 4 min.The total flavonoid extraction amount reached 26.5 mg/g,which was 1.5 times of the original material. According to the enzymolysis saccharification experiment,when the steam explosion pretreatment conditions were 2.4 MPa,2 min and the cellulase amount was 200 U/g,hawthorn pomace had the best enzymatic hydrolysis effect,and the enzymatic saccharification rate was 42.0%,which was 0.392 times higher than that of the original materials. Scanning by electron microscopy and X-ray diffractometry found that the steam explosion pretreatment made the hawthorn pomace microstructure loose. The surface area increases and the crystallinity of the cellulose decreases. Therefore,steam explosion is a very effective pretreatment method for hawthorn pomace,which provides an effective way for its development and utilization.