Abstract: Completion of the uniaxial loading experiments using industrial CT experimental system of coal samples(DT-3),and carried out a series of coal specimen tomography,accessed to the different cross-sections at the destruction of CT images.Based on image segmentation technology,the image gray level set different binarization threshold,the threshold under different pore size change curve,and puts forward to a turning point in the corresponding threshold as a slit image binarization threshold.By the threshold and the gray linear weighted average method,the coal is realized the 3D reconstruction of CT images by the Matlab software programming,and it providies a scientific basis in order to study of coal fracture 3D representation.