Polysaccharide, as a large class of natural products, has the functions of antiviral, anti-tumor, immune regulation and interferon stimulation. It has been widely used in the treatment of gastric cancer, lung cancer, breast cancer and other drugs. It has also become a hot research topic in recent years. Polysaccharide is a kind of high molecular carbohydrate composed of at least 10 monosaccharides and linked by glycoside bond. One of the remarkable characteristics of this kind of substance is that it has almost no ultraviolet absorption, or it is very weak. It has its unique method in detection means.