Ultrafine CL-20/TNT cocrystal explosive was prepared by a spray drying method.Scanning electron microscopy(SEM) was used to characterize the particle size and morphology.X-ray diffraction(XRD) and differential scanning calorimetry(DSC) were utilized to determine whether the cocrystal explosive was prepared.Furthermore, the impact sensitivity of cocrystal explosive was tested.Results show that the prepared samples are not the mix of CL-20 and TNT but rather ultrafine CL-20/TNT cocrystal explosives.The particle size of cocrystal explosives are under 1 μm and they aggregate into many microparticles, which are spherical in shape and 1-10 μm in size.The melting point of ultrafine CL-20/TNT cocrystal explosive is 132.32 ℃.The thermal decomposition process can be divided into two stages.The peak temperatures of exothermic decomposition for first and second stage are 218.98 ℃ and 253.15 ℃, respectively.The characteristic height of CL-20/TNT cocrystal explosives is 49.3 cm, which increases by 36.2cm compared with raw CL-20.