The microscopic structures of typical crystal explosives (HMX and RDX) were studied including single crystals and loose stacked crystal particles with microfocus X-ray industrial volume computed tomography (μCT). The structure information has been obtained such as nice appearance,intragranular cavities and density distribution. Results show that the high quality crystal has clear edges and corners,the crystal surface is smooth and the interior density is homogeneous but many tiny cavities in it. The surface is rough and the edges and corners are not clear for the low quality of HMX and RDX. Furthermore,the number of interior cavities is big and the density is not well-distributed and high density localities usually exist. The statistical results indicate that the cavity ratio and quantities decrease for recrystallized RDX(D-RDX) to normal RDX(N-RDX) and the less the cavities the more the amount to some degree but very small in the cavity ratio,and illustrate that level cavities greater than micron are important factor for crystal density and other performance.