The time-history mechanisms governing the seismic bending behavior of pile–slab retaining walls and associated slope deformation remain poorly understood. This knowledge gap limits the development of multilevel performance-based design methods for these structures. In this study, a series of shaking table tests was conducted on a pile–slab wall–reinforced slope with a base cover. The time-history evolution and distribution of pile bending moments, the dynamic characteristics of earth pressure, and the evolution of soil strain and displacement within the slope were systematically analyzed. The results indicate that the moment-time history of the pile-slab retaining wall can be categorized into three distinct phases. Phase 1 is characterized by a reversible dynamic moment increment, in which peak values remain constant across cycles and no residual moment develops. Phase 2 exhibits a gradual accumulation of residual moment, whereas phase 3 shows an irreversible and infinite accumulation of dynamic moment increment. The underlying mechanism is as follows: under inertial forces, simultaneous deformation of the slope and pile increases earth pressure on the pile, thereby increasing the bending moment. When soil deformation remains elastic (residual ratio = 0), no residual bending moment occurs post-earthquake. In the elastoplastic stage (residual ratio = 0–90 %), the residual bending moment increases with soil deformation. Once the soil enters the large-deformation stage (residual ratio > 90 %), the residual bending moment increases indefinitely with slope deformation. These deformation stages can be distinguished by the residual ratio of slope displacement. Although slope deformation peaks when the inertial force reaches its maximum, a phase difference exists between the peak pile bending moment and the peak deformation over time. For design purposes, the corresponding residual bending moment can be calculated from the residual displacement and then divided by the residual ratio to obtain the maximum bending moment. These findings provide theoretical support for the multilevel performance-based design of pile–slab retaining walls.