Evolution of crystal microstructure under mechanical loading, characterization technology and the change of the macroscopical properties of PBX after being pressed were summarized. The pressure, temperament, quality of crystal and bonders were concluded to analyze the reason resulting to crystal damage. The mechanism of damage′s emerging was discussed, and several kinds of modeling methods were suggested. The damage in crystal could be reduced if changing the manner of pressing, temperament in pressing, the quality of crystal or bonders. Based on manifold method, discrete element method and digital image processing technique, the model of PBX can be constructed with actual microstructures.