The banding and electronic structures of a series of long-chain macromolecules of cellu-lose,2-,3-,6-mononitrocellulose,2,3-,2,6-,3,6-dinitrocellulose and trinitrocellulose as well as theirstructural units(i.e.single-,double-or three-ring systems)have been calculated by both the EHand CNDO/2 methods.The increase of molecular total energies is consistent with the decrease oftheir stabilities at the three conformations of gg,gt and tg.The Mulliken bond order of O—NO_2bond is the samllest in each molecule at any of the three conformations,which indicates that thisbond is the weakest,and supports the view of initial homolytic cleavage of O—NO_2 bond on slow thermaldecomposition.The band gap at the edge of the first Brillouin zone far surpasses 5 eV for cellu-lose,and is less than 3 eV for mono-,di-,and trinitrocellulose.The results show that cellulose is atypical insulator,as we know,and it can be predicted that nitrocellulose has electric conductivity similarto that of semiconductor. The banding and electronic structures of a series of long-chain macromolecules of cellu-lose, 2-, 3-, 6-mononitrocellulose, 2,3-, 2,6-, 3,6-dinitrocellulose and trinitrocellulose as well as theirstructural units (iesingle-, double-or three-ring systems) have been calculated by both the EHand CNDO / 2 methods. the increase of molecular total energies is consistent with the decrease of the st st performance at the three conformations of gg, gt and tg. Mulliken bond order of O-NO2bond is the samllest in each molecule at any of the three conformations, which indicates that thisbond is the weakest, and the view of the initial homolytic cleavage of O-NO2 bond on slow thermal decomposition. The band gap at the edge of the first Brillouin zone far surpasses 5 eV for cellu-lose, and is less than 3 eV for mono-, di-, and trinitrocellulose.The results show that cellulose is atypical insulator, as we know, and it can be predicted that nitrocellulose has electric conductivity similarto that of semiconductor.