A useful method to separate the impurities from the ammonium dinitramide(ADN) product and to determine the purity of the ADN product is put forward.The results show that MIBK not only is an effective solvent to separate the ammonium nitrate(AN)impurities,but also is a good medium to chemicaly titrate the ADN.Both precision and accuracy of the purity analysis are good,the coefficient of variation is not more than 0.19%,the relative deviation of the results to be determined with two methods is not more than 0.25%.