Oligo chitosan has the function of intestinal immune regulation, detoxification, lowering blood lipids and glucose , anticoagulation, anti-inflammation and Immune system regulation, and can be used as food of patients with obesity, diabetes, colorectal cancer, and habitual constipation. Oligo chitosan can also be added to the spices, dairy products, and fruit juice, which can both enrich the taste of products, and improve the nutrition. Oligo chitosan can be applied in fruit and vegetable preservation because they keep the fruit and vegetable fresh.