Poria cocos, an important edible and medicinal material, has obvious diuretic, spleen-enhancing and tranquilizing functions. Polysaccharides are one of the most important bioactive ingredients in P. cocos. Polysaccharides from P. cocos have a variety of bioactivities, indicating their great potential in the fields of food, medicine and nutraceutical. In this paper, the structure, bioactivity, mechanism of action and structure-bioactivity relationships of P. cocos polysaccharides are systematically summarized, which will provide a basis for further development of P. cocos polysaccharides.