The purpose of this work is to describe the structure and hypoglycaemic activity of high-quality Hericium erinaceus dietary fiber (HQ-HDF), and compared with the H. erinaceus dietary fiber (HDF). Scanning electron microscopy and particle size distribution showed that the ultrasonic-microwave assisted enzymatic method significantly changed the surface structure of HQ-HDF and reduced the particle size. The results of high-performance gel chromatography showed that the ultrasonic-microwave assisted enzymatic method made the macromolecular components degrade into small molecular components. HQ-HDF has significantly improved hyperlipidemic activity in vitro. The results showed that HQ-HDF has blood lipid-lowering. The levels of total cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein in serum of high-fat mice in medium and high dose group were significantly increased. High dose of HQ-HDF significantly decreased the activities of glutamic-pyruvic transaminase and glutamic oxalacetic transaminase, increased the activities of superoxide dismutase and glutathione peroxidase. High dose of HQ-HDF could decreased the content of malonaldehyde. In addition, histopathological observation of mice liver showed that HQ-HDF could improve the lipid metabolism disorder of liver cells.