The particle size and morphology of energetic material crystal have a great influence on its performance. In order to study the relationship between crystal morphology， particle size and thermal decomposition performance of 1，1-diamino-2，2-dinitroethylene （FOX-7） explosive， FOX-7 explosive particles with different morphologies and particle sizes were prepared according to solvent/non-solvent method. Scanning electron microscope （SEM）， X-ray diffractometer （XRD）， differential scanning calorimeter （DSC） and impact sensitivity tester were used to investigate the crystal morphology and particle size， crystal form， thermal decomposition property and safety property of FOX-7 explosives， respectively. The results show that by changing the cooling rate， stirring rate and other process conditions， FOX-7 explosive particles with different morphologies such as sea urchin shape， spherical shape， flower shape and block shape can be obtained. The crystal form of prepared FOX-7 explosive is consistent with that of raw material as α-form. The crystal morphology and particle size of FOX-7 have a great influence on the breaking of intramolecular hydrogen bonds and the destruction of the conjugated system， and the spherical shape is beneficial to increase the thermal decomposition temperature. For the FOX-7 sample with a same shape， the larger the particle size， the better the thermal stability. Among the FOX-7 samples with diameters of tens of microns， the sample with spherical morphology has the best safety performance.