The N-NO2 bond dissociation energies (BDEs) for 7 energetic materials were computed by means of accurate density functional theory (B3LYP, B3PW91 and B3P86) with 6-31G** and 6-311G** basis sets. By comparing the computed energies and experimental results, we find that the B3P86/6-311G** method can give good results of BDE, which has the mean absolute deviation of 1.30 kcal/mol. In addition, substituent effects were also taken into account. It is noted that the Hammett constants of substituent groups are related to the BDEs of the N-NO2 bond and the bond dissociation energies of the energetic materials studied decrease when increasing the number of NO2 group.