Abstract：The complete stress-strain curve of rock could be divided into pre-failure and post-failure regions according to the peak stress. The post-failure mechanical characteristics of rock are important to many rock engineering cases，such as underground excavation，pillar，rock burst and so on. Therefore，the research on the post-failure characteristics of rock is of great significance to both theory and practice. In general，the post-failure region of rock shows instability in the mechanical response，which is difficult to be described by the strength softening model；and it should be described by the brittle-plastic model. Taking the axial strain rate as a constant，a series of triaxial conventional compress failure tests of Ya¢an marbles were performed by RMT–150B rock mechanics test system；and the complete stress-strain curves of rock specimens under different confining pressurees were obtained. Utilizing the stress-strain curves，the relation functions between brittle stress drop and confining pressure of marble are obtained. The achieved results can provide references，when using brittle-plastic model，to the numerical analysis of marble and its structures as well.
