Abstract: In order to reveal the microscopic mechanical mechanisms of rock stress sensitivity and to further understand stress sensitivity, a geometry and topology structure analysis was carried out using CT scanning technology which could show the actual internal structure characteristics of rocks, and can be combined with digital cores and a pore network model. Following this procedure, the relationships between effective stress,pore structure and permeability were obtained, and pore structure parameters and percolation capacities were compared during the increase and decrease of effective stress. It is shown that with the increasing of effective stress, the pore radius distribution curve shifted to the left, the shape factor probability curve shifted to the right, the pore throat connectivity became worse resulting in a decrease in permeability, and vice versa. The pore structure deformation was characterized by stress sensitivity hysteresis. After the effective stress dropped, permeability could not fully recover. In summary, it is necessary to pay attention to the effect of stress sensitivity and fluid flow on the deformation of rock pores.