In order to study the deformation and failure characteristics of the deep-buried marble in the whole process of loading and unloading, the MTS rock mechanical testing system was used to carry out triaxial loading-unloading tests with three different initial confining pressures of 25, 50 and 80 MPa, and three different unloading rates of 0.01, 0.1 and 1 MPa/s on the deep-buried marble in Jinping. The energy conversion parameter was introduced to better characterize the energy conversion characteristics before and after the stress peak. Then, a damage model based on dissipated energy was constructed in order to further explore the damage evolution state of deep-buried marble during the whole process of loading and unloading failure. The research results show that before the unloading section, it is mainly the elastic energy that accumulates in the marble; after the unloading starts, the dissipative energy becomes dominant. Ud dissipation rate>U3 dissipation rate>Ue storage rate during pre-peak unloading process, the strain energy conversion rate at the pre-peak unloading section in the marble is much higher than that under the conventional triaxial loading. Furthermore, the transformation rate of each strain energy in the post-peak stress-drop section is significantly larger than that in the pre-peak unloading section, indicating that the post-peak marble hoop expansion is intensified, and the elastic energy is rapidly released after the peak. With the increase of initial confining pressure and unloading rate, the dominant failure type changes from tensile shear failure to shear failure. The faster the dissipation rate of the post-peak dissipation energy, the more obvious the shear fracture property of the marble, the stronger the brittle failure and the smaller the damage degree. High confining pressure may inhibit the damage accumulation and expansion of the marble, whereas the insufficient expansion of the internal cracks in the marble sample at high unloading rate can cause the damage curve to rise sharply when the failure starts.