A method to determine the content of polyester in desensitized gun propellant by gas chromatography (GC) was established. The polyester was degraded by sodium hydroxied solution,and the products of degradation were analyzed by GC. Results show that there is good relationship between content of polyester and peak area. The linear range is between 3-6 g·L^-1,and the correlation coefficient is 0.996. The average recovery is 100.2%,and the relative standard deviation is 1.51%. The method is characterized by good repertability and accuracy,which shows that the method is promising in the analysis of polyester in desensitized gun propellant.