Macromolecules composed of monosaccharides of 15 molecules are called polysaccharides. Polysaccharides composed of several kinds of polysaccharides are called compound polysaccharides. Polysaccharide is a component of cells and an important cornerstone of cell function, especially it can play an important role in regulating immune function. Immunopolysaccharide has immunomodulatory effect and has no toxic or side effects. Moreover, its action points include cellular immunity and humoral immunity, which are all-round and two-way. Immunity can be improved when it is low, adjusted and normalized when it is too high, and self-stability and balance of immunity can be realized through neural-endocrine-immune network. Therefore, immunopolysaccharide is recognized as an excellent immunomodulator in the world today.