The TATB/HMX cocrystal explosive was prepared by solvent-nonsolvent method under ultrasonic assis-tance. The influence factors for the forination of TATB/HMX cocrystal were studied. The theoretical density and detonation velocity of TATB/HMX cocrystal explosive were calculated. Its characterization and thermal analysis were carried out by scanning electron microscope （SEM） , X-ray diffractometer （XRD） and differential scanning cal-orimetry （DSC） , and its impact sensitivity was tested. The results show that the optimum process conditions of pre-paring TATB/HMX cocrystal are：[Emim]Ac/DMSO as composite solvent, feed ratio of TATB and HMX as 3 ： 7, temperature as 80℃ and stirring rate as 500 r/min. The results show that compared with the raw materials the structure of TATB/HMX cocrystal molecules changes. The particle size is about 2 jj.m and the mo r p h o l o g y is hexa-gonal. The thermal stability of the cocrystal explosive is better than that of HMX. The characteristic drop height in-creases by 74cm compared with the raw HMX, revealing that the impact sensitivity is significantly reduced. Its the-oretical density is 1. 891 g/cm3 and theoretical detonation velocity is 8. 758 km/s, showing that it has good detonation performance.