Taking p-toluenesulfonic acid as catalyst,trimethylolpropane as core,the hydroxy-terminated hyperbranched polyester was synthesized by condensation polymerization of 2,2-dimethylol propionic acid.Then,the azido-terminated hyperbranched polyester was synthesized by sulfonation and azidotion of the terminal hydroxy group in succession.The structures of the target hyperbranched polyester were characterized and verified by infrared spectrum(IR),C-nuclear magnetic resonance spectrum(NMR),gel permeation in chromatography(GPC) and elemental analysis.The thermal properties of azido-terminated hyperbranched polyester were characterized by thermogravimetry(TG) and differential scanning calorimetry(DSC).Results show that the degree of branching of azido-terminated hyperbranched polyester is 0.45.The thermal decomposition of azido-terminated hyperbranched polyester has two stages.The first stage is the decomposition of the terminal azido(249.4 ℃) and the second stage is the decomposition of the main chain(350 ℃).The glass transition temperature of azido-terminated hyperbranched polyester is-55.2 ℃.