UHF-SCF-AM1 method in quantum chemistry was used to calculate thefollowing three reactions : NH₂NO₂→·NH₂+·NO₂ （1） CH₃NHNO₂→CH₃NH+·NO₂（2）（CH₃）₂NNO₂→（CH₃）₂N·+·NO₂（3）Their potential energy curves, transition states and activation energies were obtained. It is found that there is a parallel relationship between the bond order of N-N in the reactant molecules of the three reactions and the activation energy of their N-N bond breading.These results were reproduced by the corresponding PM3 calculation.