The invention discloses a radix pseudostellariae homogeneous polysaccharide for promoting insulin secretion of islet cells and use thereof. The radix pseudostellariae homogeneous polysaccharide provided by the invention is acidic polysaccharide, has a molecular weight of 4.8*10<4> Da and specific rotation [alpha] of D<25>+174.5DEG (c 0.485, H2O); the molecular formula consists of three elements: C, H, O, and C, H and O are in a ratio of 1:2.1:1.4. The radix pseudostellariae homogeneous polysaccharide is composed of monosaccharide galacturonic acid, rhamnose, galactose and arabinose, galactose uronic acid is a main monosaccharide component of polysaccharide, alpha-1, 4- connected galacturonic acid constitutes a main chain of polysaccharide. Part of galacturonic acid C6-OH undergoes methyl esterification, the hydroxyl on C2 and C3 are partly acetylized, a small amount of rhamnose exists on the main chain, and 1, 5- connected arabinose composes a branched chain. The radix pseudostellariae homogeneous polysaccharide can promote insulin secretion of Ins-1 cells, and provides the basis for application in development of anti-diabetic drugs, health care products and other fields in the future.