Abstract: The seasonal rainfall leads to a frequent wet-dry cycle environment across the China Loess Plateau. This environment often aggravates foundation settlement and collapsible deformation in loess subgrades. This study investigates the coupling mechanism of microstructural damage and macro-deformation evolution under wet-dry cycles. The findings provide a theoretical basis for engineering disaster prevention in loess regions. Artificially structured loess with controllable composition and uniform structure was prepared to simulate natural loess. This experimental approach facilitated the systematic study of the effects of wet-dry cycles (0～9 cycles) on loess. Macro-mechanical behaviors were tested using confined compression and single-line collapsibility methods. Microstructural characteristics were analyzed via Scanning Electron Microscopy (SEM), particle analysis, and X-ray Diffraction (XRD). The test results indicate that wet-dry cycling causes irreversible damage to the loess microstructure. Macroscopically, compressive deformation shows a significant positive correlation with the number of cycles. Conversely, the collapsibility coefficient follows a non-monotonic evolutionary pattern, first increasing and then decreasing. The structural parameters exhibit a non-linear decay characterized by an "initial sharp drop followed by stabilization". The first three cycles constitute the primary structural damage phase; the decay rate slows down significantly during cycles 5 to 9, reaching only about one-quarter of the initial rate. Microscopically, the dissolution and loss of cementing agents cause the soil structure to evolve. The support system transforms from a "strong cementation-large aggregate" structure to a "weak cementation-loose particle" contact system. This loss of cementing agents and the resulting microstructural rearrangement are the essential causes of macroscopic mechanical degradation. In the initial cycles, structural disintegration driven by cementation failure dominates. This significantly enhances collapsibility sensitivity. In later cycles, pore compaction and structural reorganization increase the soil's resistance to further deformation. Therefore, engineering practices must prioritize waterproofing during the early exposure period of the foundation to prevent sudden settlements caused by accumulated structural damage.