A kind of desensitized octogen (D-HMX) was characterized with various analysis methods, including Optical Microscopy with Matching Refractive Index(OPM), Scanning Electron Microscopy(SEM), Laser Particle Sizer, High Performance Liquid Chromatography (HPLC), density gradient technique and X-ray Diffraction(XRD). The thermal properties of D-HMX were investigated by Differential Scanning Calorimetry (DSC) and Vacuum Thermal Stability test(VST). The sensitivities of D-HMX against friction, impact and shock were studied. Compared with conventional octogen (C-HMX), D-HMX has better morphology, lesser crystal defects, better thermal properties and takes great effect on reducing shock sensitivity in both cast and pressed PBX formulations. Which are incarnated from the following aspects. First, the D-HMX has no twinned crystals or congeries, which shape is regular polyhedron and nearly spheric. Second, there are no inclusions in D-HMX crystals, the purity of D-HMX is (99.6±0.1)% and the mean particle density is great 1.9016 g?cm^-3. Third, the results of DSC and VST show that the β→δ phase transition of D-HMX is shifted to high temperatures about 6 ℃ and that the amount of gas evolution of D-HMX is obviously less after being heated for 48 h at 120 ℃ compared with C-HMX. Fourth, the results of shock sensitivities demonstrate that the aluminium gap thicknesses of cast and pressed PBXs based on D-HMX are lesser 10%~23% than that of PBXs based on C-HMX. Additional, the impact sensitivity of D-HMX appears lower sensitivity than C-HMX. Especially for the fine grain D-HMX(FD-HMX), the drop-height of 72.2 cm and initiation probabilities of 24% indicate there are significantly higher resistance to impact than the fine grain C-HMX(FC-HMX) of 16.8 cm and 88%.