The semiempirical AM1 method is used to optimize the geometry of hexanitrohexaazaisowurtzitane (HNIW),compute and analyze the vibration frequency. Furthermore a discussion of the strong absorption characteristic peaks of -NO₂ is presented as well as its comparison with the experimental IR spectra. According to the population and analysis the molecular structural stability is discussed. The bondshaping characteristics of N-NO₂ are analyzed by the NBO and BO methods.