It was found that polysaccharide has the characteristics of low toxicity， high efficiency and good biological activity， and it is widely used in the prevention of gastrointestinal diseases. Based on an overview of the source and chemical structure of polysaccharides， this paper systematically analyzed the regulatory mechanisms of different kinds of polysaccharides on gastrointestinal function and their protective effects on gastric mucosa， providing new ideas for exploring the biological activities of polysaccharides and their mechanisms of action in the body， as well as the regulatory mechanisms of gastrointestinal diseases.