Hyperbranched aliphatic polyesters were synthesized in the molten state from 2,2-bis(hydroxymethyl) propionic acid and 2-ethyl-2-(hydroxymethyl)-1,3-propanedio(core molecule) by using p-Toluenesulfonic acid catalysis. The synthesis procedure was a pseudo-one-step reaction which stoichiometricamounts corresponding to each generation were added successively. The polyesters with hydroxyl groups as terminal groups were glassy solids at room temperature. The chemical structures and properties of these polymers were characterized by ,13,C NMR, FT-IR, GPC, DSC. One of the polymers was further modified by stearic acid and methacrylic acid to form a hyperbranched polymer terminated in stearic and methacrylic groups partially, which could be used as main resin in UV-curable powder coatings system.