Abstract: The central segment of the Western Sichuan Depression, located on the western margin of the Sichuan Basin, has been influenced by the Longmen Shan orogenic belt and has experienced multiple phases of tectonic movement and superimposed modification, resulting in the formation of a complex deep-shallow dual-layer structural system. Based on high-precision three-dimensional seismic data from the central segment of the Western Sichuan Depression, this study conducts fine structural interpretation, selects profiles of typical buried detachment anticlines, and applies the area-depth-strain (ADS) method to perform quantitative analysis of multi-phase structural deformation. In combination with regional structural deformation characteristics, it systematically investigates the structural deformation mechanisms and basin-mountain coupling processes in the central segment of the Western Sichuan Depression. The results show that, bounded by the Middle-Lower Triassic gypsum-salt detachment layer, the central segment of the Western Sichuan Depression is vertically decoupled into a shallow frontal thrust-nappe system in the piedmont and a deep buried detachment deformation system within the basin. The structural deformation in the study area exhibits a segmented pattern along strike, with deep deformation weakening from south to north and shallow deformation strengthening from south to north. This segmentation results from the combined effects of heterogeneous compression of the orogenic belt, differences in basement structure, and spatial variations in the detachment layer. Combined with the ADS quantitative analysis results of detachment anticlines, this study suggests that the multi-phase deformation of detachment anticlines in the central segment of the Western Sichuan Depression displays a pulsed distribution pattern of “early Indosinian deep-level initiation (217 m), middle Indosinian shallow-level dominance (142 m), and late Indosinian overall waning (≤31 m)”, quantitatively revealing an episodic pattern in which the basin-mountain compressional deformation was transferred from deep to shallow levels and from early to late stages. Meanwhile, the differences in shortening amounts between the deep and shallow deformation systems in anticlines A and B indicate a “staggered peak” response over time: the deep deformation system experienced significant shortening during the early Indosinian (anticline B shortening of 217 m), whereas the shallow deformation system responded most strongly to compression during the middle Indosinian (Anxian Movement), together forming a unique coupling style of “deep pre-existing folding–shallow thrust nappe”. The “vertical layering–lateral segmentation–multi-phase quantification” structural understanding system established in this study not only provides a quantitative structural basis for deep to ultra-deep petroleum exploration in foreland basins, but is also of great significance for deepening the understanding of the basin-mountain coupling processes in the central segment of the Western Sichuan Depression.