Abstract: 5-Hydroxylevulinic acid (5-HLA) was synthesized via modified bromination and hydrolysis using levulinic acid (LA) as starting material. Based on the hydroxyl and the carboxyl groups of the 5-HLA, poly(5-hydroxylevulinic acid), a novel aliphatic polyester, was synthesized by direct polycondensation using SnCl₂•2H₂O as catalyst. In addition, 1,6,9,13-tetraoxadispiro ［4.2.4.2］tetradecane-2,10-dione (or altaicadispirolactone), a dimer of the 5-HLA, was synthesized by cyclolactonization catalyzed by BF₃•OEt₂. Altaicadispirolactone is one of the chemical components of Anemone altaica C.A.May, a traditional Chinese medicinal material. Structures of the dimer and the polymer were characterized with GC-MS,¹H NMR, FT-IR, element analysis and GPC, respectively. Two plausible mechanisms for the cyclolactonization reaction were presented.