Abstract: Polysaccharides are important natural products exhibiting many biological functions, such as antioxidant, anti-inflammatory and anti-tumor activities. They are widely used in food and pharmaceutical industries. The extraction method affects the yield, structure and activity of polysaccharides, influencing their application. Subcritical water extraction is environmentally friendly, non toxic and with high extraction efficiency. It is widely used in the preparation of natural products. Under high temperature and high pressure, subcritical water changes the polarity and dielectric constant of the solvent, thereby improving the mass transfer efficiency, in the meantime maintaining the biological activity of the extracts. In this paper, we introduced the basic principles of subcritical water extraction and summarized the application of subcritical water in the extraction of fruits and vegetables, edible fungus, seafood and other polysaccharides and modification , which provides theoretical basis and references for further researches on the application of subcritical water extraction technology in polysaccharide preparation.