Abstract: The inner defect of explosive crystal is one of the key factors that affect the performance of explosive material.The structure of typical crystal explosive(HMX) is studied with microfocus x-ray industrial volume CT(μVCT) and the micro hole ratio is quantificationally analyzed in this paper.The results indicate that micron holes are extensively presented in HMX crystal and the micro hole ratio is up to 1%~2%,which reveal initial damage existence in explosive parts and the difference between theoretical density and actual density of crystal.The micro hole of HMX crystal may reduce effectively and density and performance are improved after a certain technical treat.The inner structure and micro hole ratio measurement can be effectively studied with μVCT for HMX crystal over tens of micron.This research provides an intuitionistic reliable experimental means for studying molding performance and damage destruction mechanism of explosive parts.