To investigate the effects of external electric field on sensitivity of HMX/MDNI, different external electric fields (-0.010-0.010 a.u.) were employed on M06-2X//B3LYP/6-311++G(d, p) level by quantum mechanics method. The intermolecular interaction, trigger bond energy, electron density topological, electron density shifts and electrostatic surface potential of complexes were considered with different external electric fields. It shows that trigger bond length is shorter and bond dissociation energy is larger with the increasing of external electric field along the positive direction, while the trend is opposite along the negative direction. The correlation coefficients for 3 complexes (by B3LYP) are 0.995, 0.977 and 0.982, respectively. Q_NO2are decreasing with the negative external electric fields, indicating the sensitivity is increasing. Electron density topological analysis shows that there are weak hydrogen bond interactions between HMX and MDNI with external electric fields. Electron density shifts analysis shows that positive external electric field strengthens the trigger bond. Electrostatic surface potential indicates that sensitivity of explosive is decreasing in the positive external electric field, while increasing in the negative direction.