Abstract: To investigate the effects of steam explosion (SE) pretreatment on the extraction, physicochemical properties of polysaccharides from Hericium erinaceus residue and their in vitro gut microbiota fermentability characteristics, water-extracted residues of Hericium erinaceus fruit bodies were treated by conventional crushing and SE to prepare crude polysaccharide fractions. Results showed that the yield, polysaccharide and β-glucan content of SE pretreated fraction (HCQ) reached 13.36%, 58.20% and 47.93%, respectively, which were 2.18, 1.57 and 1.59 times that of HCW obtained by conventional crushing treatment, suggesting that SE could significantly (P<0.05) promote the release of polysaccharide components from the residues. SE also reduced the molecular weight of HCQ and released small molecular fractions, while increasing the molar ratio of glucose in monosaccharide composition. During in vitro fermentation by human feces process, HCQ could obviously (P<0.05) improve the abundance of beneficial bacteria (such as Firmicutes) and the production of short-chain fatty acids, while reducing the abundance of harmful bacteria (such as Escherichia-Shigella) than HCW, which could be beneficial to human body health. This research provides a basis for the application of SE in the preparation of polysaccharides from Hericium erinaceus residues and the potential role of HCQ as prebiotics in positively regulating gut microbiota.