Abstract: Triaxial compression experiment was carried out to investigate localized progressive failure mechanism of rock material by rock mechanics test equipment RMT-150C.Based on the experimental results,the complete stress-strain relation was analyzed,post-peak tow phases of stress-strain curve were discussed,and the failure mechanism of rock material was studied.The results show that the stress at post-peak stage occur a progressive fall,tend to stability and reach the residual strength.At the same time,the model which can simulate the process of strain softening and localize progressive failure is established,in virtue of the formation process and mechanism of localization shear zone.Finally,the results calculated through aboved model agree well with the experimental results,which prove the model is reasonable.