Abstract：In laboratory tests of rocks，the macro shear-bands can be observed clearly during the collapse of the specimens. According to the relative standards and specifications for rock tests，the specimens which have standard shape and size and standard test conditions are taken. With software FLAC3D，the formation processes of localization shear-bands of rock specimens under axial symmetric compression are simulated. Under the uniaxial compression，the formation of strain localization of the rock specimen is steady. With the increase of the axial strain of the rock specimen，the localization network forms firstly，then approaches in an inclined section and forms a macroscale shear band finally. Under the general triaxial compression，when the lateral pressure is not very high，the formation process of the rock specimen is very similar with that under the uniaxial compression. But when the lateral pressure is very high，no macroscale shear-band forms when the rock specimen fails. The inclination angles of the shear-bands of rock specimens are almost the same under several lateral pressures，and all are less than the Mohr-Coulomb fracture angle. The complete stress-strain curves of rock specimens present similar laws. The numerical simulation results are basically consistent with test results.
