Abstract: Isaria felina was a new strain of Cordyceps sinensis that had been separated from the fructification of natural Cordyceps sinensis. The purpose of this article was to study the optimum extraction technology of polysaccharide from Isaria felina. The method of liquid fermentation was used to culture Isaria felina, the method of water extraction and alcohol precipitate was used to isolate polysaccharide from the mycelium of Isaria felina, and the method of phenol-sulfuric acid was used to determine the content of polysaccharide. Through the single factor and orthogonal test, result showed that the optimum extraction conditions were as follows:the ratio of water and mycelium powder was 6:1, the extract was concentrated to twice the weight of mycelium powder and the ethanol ratio was four times the volume of the concentrated extract. Under this condition, the extraction rate of polysaccharides was 16. 24%.