Two types of porous reticular HMX, PHMX-A and PHMX-B, were prepared by adding octogen(HMX)/ dimethylsulfoxide(DMSO)complex, which was obtained by mixing HMX and DMSO, into pure distilled water or the solution containing polyvinyl pyrrolidone. Their structures were characterized by scanning electron microscope, X-Ray diffraction, mercury pressure method and thermogravimetry-differential scanning calorimetry. Results show that both porous reticular HMXs are consist of homogeneous continuous skeleton and many pores, and have high specific surface area and porosity. PHMX-A is absolutely β-type crystal, while PHMX-B contains a little γ-type crystal. The SSAs for PHMX-A and PHMX-B are 5.3 m²·g^-1 and 19.0 m²·g^-1, the mean pore diameters are 501nm and 75nm, and the porosities are 56.1% and 37.2%, respectively. The phase inversion temperature, thermal decomposition temperature and initial decomposition temperatures for PHMX-A and PHMX-B compared with those of raw HMX, are all advanced by 2.8 ℃ and 17.5 ℃, 0.3 ℃ and 1.3 ℃, 4 ℃ and 14 ℃, respectively.