Abstract：The crack propagation mechanism of the rock-like material that is carefully selected through comparison of similar physico-mechanical parameters is studied. The CT real-time scanning tests of the rock specimens with artificial single initial disk-like fracture are carried out to study the propagation mechanism of the 3D crack under compression stresses. From CT image analysis，it is preliminarily determined that the failure of the specimens is caused by the damage evolution of the crack. From the comparative analysis of CT values and CT variances in manifold areas，some valuable information and important parameters are obtained with increasing load as follows：(1) the courses of compressed crack；(2) self-similar propagation；(3) wings growth；(4) micro-cracks propagation；(5) cracks joining；(6) cracks accelerated growth；(7) damage evolution course of the specimen failure and the parameters of initial propagation strength；(8) propagation length of wing crack；and (9) self-similar propagation length of crack，etc.. The stress-strain curve is divided into four sections before failure of the specimen，and damage propagation mechanisms of initial fracture is given.
