polysaccharide has become a research focus in tumor therapy because of possessing positive immunomodulating and antitumor activities.At present,a series of polysaccharides with novel structures and unique function have been isolated from marine resources,which are potential choices for anti-tumor drugs.However,few reviews are reported about the antitumor mechanism of marine polysaccharide,so the progress in research of antitumor mechanisms of marine polysaccharide are reviewed in this paper.