The molecular geometries and electronic structures of the four conformations of PDADN arc fully optimized by using the semi-empirical AM1-MO method.Among the four conformations, the structure with one-ONO₂ group at trans-conformation and another-ONO₂ and two-N₃ groups at cis-conformations is the most stable.When all four groups,two-ONO₂ and two-N₃,are at trans-conformations,the nuclei repulsion energy is lower and the dipole moment is smaller than those in other conformations.