In order to study the morphology evolution of 1， 1-diamino-2， 2-dinitroethylene （FOX-7） particles under thermal stimulus and its influence on mechanical properties and mechanical sensitivities， four kinds of FOX-7 particles with typical size and morphology differences were selected. By controlling heating time and temperature， the morphology， mechanical properties and mechanical sensitivities evolutions of FOX-7 particles after heating were studied by scanning electron microscope， compressive stiffness experiment and mechanical sensitivities tests. The results show that the surface cracks of FOX-7 particles appear after heating and returning to room temperature. With the increase of heating temperature or heating time， the surface cracks of large-size particles （>100 μm） grow and break through ， thus the particles crack in layers and exfoliate. While， the surface cracks of small-sized particles （<100 μm） do not grow with the increase of heating temperature or heating time. Kawakita equation was used to fit the compaction curves of FOX-7 particles before and after heating. It is found that the modulus of FOX-7 particles increase after heating， and the increase is even greater for small particle size. Under the condition of larger particle size， FOX-7 has relatively low mechanical sensitivities， and still maintains low mechanical sensitivities after being heated and returning to room temperature. When the particle size is small， the mechanical sensitivities of FOX-7 are relatively high， and after heating and returning to room temperature， the mechanical sensitivities increase significantly， which may be related to the greater increase of modulus.