Abstract: As the research progressed, researchers found that not all polysaccharides were active or had only weak activity, which was affected by the chemical structure of the polysaccharides. Therefore, taking effective methods to modify the structure of polysaccharides was an effective way to enhance the biological activity of polysaccharides and promote the production of activities. It had important practical significance to study the structure-activity relationship of polysaccharides and the development and utilization of polysaccharides. At present, the methods of structural modification mainly included chemical modification, physical modification and biological modification. Based on these three modification methods, this paper reviewed the recent researches on domestic and international structural modification of polysaccharides from the aspects of their modification methods, principles and their biological activities. The specific method of chemical modification and its effect on the biological activity of polysaccharides were emphatically introduced, providing reference for intensive study and exploration of structure modification of polysaccharides and development and application of polysaccharides products.