Abstract: This study aimed to develop a new and efficient technology to extract crude polysaccharides from Tremella fuciformis with hot water and study their physicochemical properties and functional activities. Fresh Tremella fuciformis produced in Gutian, Fujian Province was selected as the raw material, crude polysaccharides were extracted by hot water extraction method. The optimum technological conditions were obtained by orthogonal test. Afterwards, physical and chemical properties, antioxidant capacity, hypoglycemic and hypolipidemic activity of these polysaccharides were analyzed through the determination of basic components, fourier infrared spectroscopy, DPPH, ABTS and hydroxyl radical scavenging capacity and the inhibition rate of them on α-amylase and α-glucosidase activity, etc. The results showed that the optimum extraction conditions were:liquid material ratio 70:1 mL/g, extraction temperature 90℃ and extraction time 4 h. Under this condition, the yield of crude polysaccharide was 19.06%. The total sugar content of Tremella fuciformis crude polysaccharide was 80.56%, the uronic acid content was 9.07%, the protein content was 0.08%, and the average molecular weight distribution was 4.86×10⁶ Da. Tremella fuciformis crude polysaccharides were mainly composed of fucose, galactose, glucose, xylose, mannose and glucuronic acid, and their molar percentages were 11.20%, 1.20%, 15.00%, 15.30%, 49.50%, and 7.70% respectively. The characteristic peaks at 3 400 cm^-1, 2 900 cm^-1 and 1 400 cm^-1 wave numbers in the infrared spectrum showed acidic heterocrude polysaccharides. The IC₅₀ of DPPH, ABTS, and hydroxyl radical scavenged by crude polysaccharide samples were 0.05, 1.72, and 0.14 mg/mL, respectively. the IC₅₀ of crude polysaccharides inhibiting α-amylase and α-glucosidase were 1.09 and 4.15 mg/mL, respectively; the cholesterol binding rate and sodium cholate binding rate of crude polysaccharides in vitro were 16.96% and 51.41%, respectively. According to the antioxidant experimental data, crude polysaccharides had certain antioxidant activity, and the inhibitory effect of crude polysaccharide on two enzymes and the binding rate with cholesterol and sodium cholate indicated that crude polysaccharides of Tremella fuciformis had certain hypoglycemic and lipid-lowering effects. Moreover, this method can also retain the original structural characteristics and biological characteristics of polysaccharides from Tremella fuciformis to a great extent. This study provided a theoretical foundation for the application of Tremella polysaccharides in flour products in the future.