A polysaccharide is a macromolecular polymer composed of more than 10 monosaccharide molecules through condensation and dehydration, and it is an essential substance for life. However, most plant polysaccharides cannot be digested by enzymes encoded by the human genome. The intestinal flora consists of a variety of microorganisms that reside in the gastrointestinal tract of the host, including Bacteroidetes and Firmicutes as well as lesser quantities of Actinobacteria and Protebacteria, which can secrete polysaccharide-degrading enzymes to promote the digestion and absorption of polysaccharides. Non-digestible polysaccharides and short-chain fatty acids (SCFAs) in the fermentation products can further regulate the composition of the intestinal flora, improve intestinal function, and participate in regulating the expression of anti-pathogenic microorganism, anti-inflammatory, anti-tumor genes, thereby treating diseases and maintaining health. This article summarizes recent progress in understanding the interaction between polysaccharides and the intestinal flora, which will provide a scientific basis for further studies on human health and rational diets.