Abstract: Many researchers have confirmed that natural polysaccharides have the effects of antioxidation, anti-aging, anti-tumor, reducing blood glucose and regulating intestinal flora. Consequently, natural polysaccharides have good development potential and application prospects in the fields of biomedicine, food, and health products. Recently, the extraction, purification, physicochemical properties, and bioactivities of natural polysaccharides have been drawing much attention from scholars around the world. However, different raw materials, extraction, and purification methods lead to differences in the structure and bioactivities of natural polysaccharides. This paper systematically reviews the latest extraction, separation and purification methods, and the hottest biological activities of natural polysaccharides to provide an important reference for plant polysaccharides as functional food and effective therapeutic drugs, and provide an important basis for the development of food based on human health in the future.