Abstract:To explore the characteristics of fatigue deformation of red-sandstone under triaxial compression with cyclic loading,complete stress-strain tests under different confining pressures are performed with multi-function apparatus RMT–150B. Testing result shows that the terminal strain corresponding to fatigue failure is equal to the one corresponding to the point that the post-peak stress-strain curve and the line of the maximum cyclic load(s1-s3) are intersected. The development of irreversible deformation shows a law of three stages. The maximum of cyclic load and amplitude have remarkable effects on fatigue failure of red-sandstone.