The present invention provides a method to prepare polysaccharides from Hirsutella sinensis. The prepared polysaccharides reduce body weight and fat accumulation, and can therefore be used to prevent and treat obesity.本發明係提供一種使用中華被毛孢多醣體用於抑制肥胖之用途,其中該中華被毛孢多醣體係用於減輕體重與脂肪蓄積,並因此可用於預防和治療肥胖症。本發明另提供該中華被毛孢多醣體的製備方法。