Polysaccharides widely exist in animals, plants, microorganisms, and possess various biological activities including anti-tumor, anti-virus, anti-oxidant and immunomodulatory. Polysaccharides shows notable anti-tumor activity and less toxicity, and becomes a hotspot in the studies of anti-tumor drugs. Therefore, there is huge potential for developing polysaccharides into a novel antitumor medicine. This article summarized polysaccharides derived from animals, plants, microorganisms which have significant antitumor effect in the latest 5 years; findings indicate that polysaccharides show the anti-tumor effect directly by inducing tumor cell apoptosis and indirectly as an immunoenhancement. This article also looks into the future of studies on anti-tumor activity of polysaccharides.