Marine polysaccharides， including seaweed polysaccharides， marine animal polysaccharides and marine microbial polysaccharides， are a class of polysaccharides isolated and purified from marine and lake organisms， which have the function of adjusting gastrointestinal function， regulating blood sugar and lipid value， controlling obesity， anti-radiation， anti-tumor， anti-aging and a series of biological activities. The types and structures of ocean polysaccharides， their effects on intestinal flora， and their regulatory effects on host nutrient metabolism were reviewed in this manuscript， aiming to provide the reference for further research on marine polysaccharides function.