The extraction of conventional water-insoluble polysaccharides is usually performed by a chemical process, a fermentation process, a biological enzyme process and the like. In the chemical process, the extraction vessels, tubes and material pumps are seriously corroded by the used strong acid, strong base and high-temperature treatment, and the acidity needs to be regulated repeatedly during the extraction, a large number of zwitterions is introduced and the prepared water-insoluble polysaccharides have a lower content and a poor color. In the fermentation process, the prepared water-insoluble polysaccharides has a high active ingredient content and light pollution, but has a long production period, a high cost, and an unfavorability for the scale production. In the method, the water-insoluble polysaccharide of a mushroom is extracted by the enzyme process and has the advantages of high content, no introduced chemical agents, high purity, and continuous production. Meanwhile, by using the ultra-micro crushing technology, the physiological activity function of the product is improved, and an own unique production process and mature complete technology are formed.