For different practical projects, conducting experiments with different stress paths to study the mechanical characteristics of rock masses is the key to solve practical problems. In order to study the mechanical characteristics of siltstone under the special stress path of cyclic unloading-loading of confining pressure, the MTS815 rock mechanics test system was used to conduct graded cyclic unloading-loading confining pressure tests at different axial force levels, and the evolution characteristics of axial and circumferential plastic strain and elastic modulus at different axial force levels were analyzed and studied. The relationship between the energy evolution and the deformation and damage of the specimens was also analyzed by combining the calculation of dissipated energy. The results show that the hysteresis loops move in the direction of strain increase as the number of cycles increases, and the stress-strain curves of unloading-loading confining pressure gradually close, and the overall change of hysteresis loop spacing is from "sparse" to "dense". The lower the unloading level, the lower the modulus of elasticity, and the lower the axial force level, the higher the modulus of elasticity; the modulus of elasticity is affected by both the axial force level and the unloading level; the circumferential plastic strain is always larger than the corresponding axial plastic strain in a single cycle, and the resistance to plastic deformation is stronger at high axial force levels than at low axial force levels under the special stress path of cyclic unloading-loading confining pressure; the total energy dissipated in the final damage of the rock is somewhat different from the axial force level.