The Ganoderma lucidum polysaccharide is a macromolecular compound which is dehydrated and condensed from one or more monosaccharides by a reducing end group C1 of one sugar and a hydroxyl group of another sugar C2, C3, C4 or C6. It has the properties of the original monosaccharide and becomes an odorless carbohydrate. Ganoderma lucidum polysaccharide, soluble in water (warm, hot), insoluble or poorly soluble in alcohol (ethanol, methanol), ether, acetone and other organic solvents. A few are soluble in solvents such as dimethyl sulfoxide. Soluble in dilute alkali, dilute acid solution. Therefore, by utilizing the solubility properties of the polysaccharide, the laboratory usually uses hot water extraction, that is, heating is extracted at 90-100 ° C with water as a solvent, and after the extract is concentrated, several times of ethanol is added to precipitate the polysaccharide, and the obtained polysaccharide is obtained. Containing protein impurities, the laboratory uses the Sevag method (1 chloroform + n-butanol 5:1 V / V; or 2 chloroform 1 / 5 + isoamyl alcohol 1 / 15 V / V) to remove free protein. The method comprises the steps of: adding a mixture of chloroform + n-butanol (5/1 V/V) to a crude polysaccharide aqueous solution, shaking it a plurality of times, denaturation of the protein, removing in the emulsion layer, and repeatedly operating to remove free protein. The small molecule impurities were removed by dialysis, and ethanol was added to precipitate the polysaccharide into a total polysaccharide (crude polysaccharide) of Ganoderma lucidum. In the extraction, first with ethanol or methanol in the same stream, the residue is removed from the alcohol and then extracted with water, also treated with dichloromethane, and then extracted, but to prevent degradation, the alkaline extract should be quickly neutralized, dialysis It is also possible to precipitate an alkali-soluble polysaccharide by acid or ethanol.