Abstract: In the water-level fluctuation zones of clastic rock bank slopes, mudstone is subjected not only to dry-wet cycles but also to the persistent self-weight stress of overlying rock strata. To investigate the mechanical properties and energy evolution mechanisms of mudstone under coupled conditions, tests under the coupled action of multi-cycle stress and wet-dry cycles are conducted. The results show that: ①The compressive strength and deformation parameters of mudstone exhibit a significant deterioration trend with increasing test cycles, with the deterioration rate being the fastest in the first 5 cycles, accounting for more than 70% of the total deterioration. The overlying stress has a significant accelerating effect on the deterioration of mudstone's compressive strength. Under a stress of 0.6 MPa, the rock strength decreases by 28.8% compared to the stress-free state; ②With the increase of test cycles, the total strain energy density, elastic energy density, and dissipated energy density of the specimens all present a decreasing trend, and the overlying stress exacerbates the deterioration of these three energy densities, with the three energy densities decreasing by 23.8%, 27.4%, and 4.8% respectively under a stress of 0.6 MPa compared to the stress-free state. ③The results of microscopic tests indicate that the overlying stress promotes the development and penetration of fractures. Which provide seepage channels for dry-wet cycles. The microscopic structure of mudstone is significantly damaged, gradually transforming from the initial dense structure to a disordered and loose one, thereby leading to the deterioration of mudstone mechanical properties. The research can provide a reference for the stability analysis of clastic rock bank slopes in the Three Gorges Reservoir area.