Plant polysaccharides are natural biological active substances, and possess a series of biological activities, including anti-tumor, immune regulation, lowering blood fat, lowering blood sugar, anti oxidation, anti-fatigue. The activities of polysaccharides are influenced by their species, parts, extraction methods and other factors. In order to provide a theoretical reference for the development and utilization of plant polysaccharides, the research status of them and the effects of extraction methods on their biological activities were reviewed in this paper.