Abstract: To resolve the dispersant of nanometer material in polymer matrix,this article provided a method to prepare polyester nanocomposites by in-situ polymerization.The nano-scale zinc carbonate hydroxide was prepared with ammonium carbonate and zinc sulfate,and then the glycol solution of barium hydroxide was added to this reaction system to obtain a multiple nanometer compounds suspension,which was added to the polymeric reaction kettle directly without separation.Decomposed at the reaction temperature,CO2and H2O were emitted so that to avoid the secondary aggregation of particles,the reaction in situ was carried out,thus got the modified polyester chips.The technical parameter and thermal property were determined respectively.The TEM image showed that the inorganic nano-particles were dispersed equably in the matrix.