Abstract:Rock is heterogeneous. Rock deformation is nonlinear,and depends on the loading path. Various loading and unloading paths are carried in servo-controlled testing machine to study the relationships among axial stress,strain,confining pressure and circumference deformation. Specimen’s deformation will become more linear after it is loaded and unloaded under elastic condition. The tangential value of Poisson’s ratio and Young’s modulus can describe specimen’s deformation changed with stress state . That means the variance of stress and strain,not the stress and strain themselves,satisfies the Hooke Law. The bearing capacity of specimen is constituted by material strength and internal friction,which is related to confining pressure. The specimen can bear bigger axial stress by increasing confining pressure after its material strength is weakened. Although axial stress is increasing,it can weaken continually to produce more plastic deformation. The effect of ratio loading path on the limit loading and the process of specimen’s yield is quite small.