Ring-opening polymerization(ROP) of glycolide was studied in the presence of l-dodecanol as molecular weight regulator and tin(П) 2-ethylhexanoate(Sn(Oct)2) as catalyst.The highest molecular weight polyglycolide(PGA) was synthesized with intrinsic viscosity 3.848 dL/g.PGA with controlled intrinsic viscosity ranging from 2.278 dL/g to 3.218 dL/g was obtained by the addition of different contents of l-dodecanol.The structure of PGA was characterized by Fourier transform infrared spectroscopy(FT-IR) and nuclear magnetic resonance(1H-NMR).The PGA was characterized by X-ray diffraction(XRD),differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The results show that PGA is a semicrystalline polyester with high crystallinity and good thermal properties.The crystallinity is 48.72% and the melt temperature is between 222 ℃ and 224 ℃.