Abstract: Tea polysaccharides have been reported in their excellent effects for decreasing blood sugar, especially in prevention for diabetes.The tea polysaccharide is defined for conjugated polysaccharides comprised of various monosaccharide, proteins, pectin and ashes.In recent years, studying for component profile of tea polysaccharides has become a favorite topic including monosaccharide composition, molecular weight, glucosidic bond, conjugated method and conformation changes.Among the bioactivities, the most prominent effect of tea polysaccharides is decreasing blood sugar that is correlation to its function in antioxidant and regulating metabolic enzymes for sugar.This paper reviewed literatures for tea polysaccharides in composition, structure and effect on decreasing blood sugar for further studies.