The present invention provides a method to prepare polysaccharides from Hirsutella sinensis. The prepared polysaccharides can reduce liver weight and liver vacuolation, as well as serum triglycerides and aspartate aminotransferase levels in humans and animals, and can therefore be used to prevent and treat fatty liver disease.本發明提供一種使用中華被毛孢多醣體用於治療或預防脂肪肝疾病之用途及其製備該中華被毛孢多醣體之方法。本發明之中華被毛孢多醣體可降低一個體的肝臟重量與肝臟液泡,亦能降低血清中三酸甘油酯與天冬胺酸轉胺酶(aspartate aminotransferase)含量,因此可用於預防與治療脂肪肝疾病。