Abstract: In order to study the image fractal dimension of each scanning section and the variation law of the porosity before and after the loading on the coal-rock,the industrial CT detection technology and the triaxial loading test system were applied to the CT scanning observations on the initial coal-rock and the loading damaged coal-rock under the triaxial condition. An analysis was conducted on the density distribution images of the coal-rock CT sections and the dynamic failure process of the coal-rock under the role of the loading. The study results showed that the fractal dimension and porosity of the coal-rock before and after the failure of different section were different in variation. Under the same stress state,the different section of the coal-rock would have different damage expansion features. Under the role of the loading,the damage evolution of the coal-rock would be a localization and inhomogeneity. With an analysis on the density curve of the coal-rock grey probability,a multimodal distribution occurred in the curves was obtained and could explain the multi damage factors existed in the coal-rock. A single protruding peak existed in the curves could explain one factor in the leading position of a factor. The test results and the coal-rock dynamic damage process combined with the deformation damage features of the coal-rock and with the selection of the suitable damage parameters were applied to establish a damage constitutive model of the coal samples under the role of the loading. The results showed that the theoretical curve and the test curve could be well fitted.