Metabolic syndrome is a metabolic abnormal disease containing multiple components， and its incidence rate is gradually increasing. Bioactive substances in marine food， such as marine polysaccharides， bioactive peptides and saponins， have been paid more and more attention because of its unique structure and hypoglycemic， hypolipidemic， anti-hypertensive and immune regulation. The mechanism of improving metabolic syndrome by marine polysaccharides， bioactive peptides and saponins in marine food are summarized to provide reference to the applications of these bioactive substances. For example， marine polysaccharides improve glycolipid metabolism by regulating the composition of intestinal flora and degradation into short chain fatty acids. The mechanism is that Lactobacillus， Bifidobacterium and other beneficial bacteria improve the related functions of intestinal tract and immune system， as well as the combination of short chain fatty acids and G-protein-coupled receptor 40 family. By regulating the secretion of satiety hormone， it can reduce appetite and increase energy consumption， so as to improve metabolic syndrome and achieve balance between quantity and metabolism.