Abstract: Three typical seepage curves are obtained using fractured seepage tests based on diffirent pressures. The main factors affecting the sample permeability are discussed. The fractures would be deformed under the condition of positive stress and be ruptured and extended under the condition of shear stress. The permeability variation of fractures is also analyzed during fracture deformation, rupturing and extension. The mechanisms of three typical seepage curves, which seem to abnormal but actually normal, are explained under the condition of stress. At the same other conditions, the relationship between permeability and stress of samples is determined by the angles between stresses and fractures.