Abstract: The dominating impurity triacetyltribenzyl Hexaazaisowurtzitane(TATBIW) was synthesized in the first hydrogenolysis of hexabenzyl Hexaazaisowurtzitane(HBIW). The purification of TATBIW was carried out through column analysis.Triacetyltriformyl Hexaazaisowurtzitane(TATFIW) was synthesized in the second hydrogenolysis of TATBIW(the purity>99.99%),and identified by IR and MS.By means of Gaussian 98 packages software,at the level of B3LYP/6-31G,the structure of TATFIW has been optimized.The IR spectrum and the thermodynamic character of TATFIW were calculated.The calculated and the experiment IR harmonic frequencies and intensities of TATFIW are listed,and the relative error of harmonic frequencies is found to be less than 3%.Judging from the analysis of the structure,the dominating impurity in the process of synthesizing HNIW is pentanitroformyl Hexaazaisowurtzitane(PNMFIW) existing in the nitryl-sulfuric acid agent.