Abstract: The structural failure of unsaturated loess under hydraulic action significantly contributes to its collapsible behavior. However, prior research rarely utilized computed tomography (CT) scanning to explore the spatiotemporal relationships between water infiltration dynamics and loess deformation and microstructural evolution during collapse. This study investigates unsaturated Q₃ loess and its remolded version using a self-developed micro-CT triaxial apparatus for controlled isotropic loading infiltration tests at confining pressures of 50 to 300 kPa. Real-time dynamic scanning of longitudinal cross-sections of the specimen provides insights into the mechanisms of water infiltration, structural damage, and collapse deformation throughout the wetting process. Results show that the collapse volumetric strain in undisturbed loess is 20.5% to 90.4% higher than that of remolded loess under identic confining pressures, accompanied by a shorter collapse response time. CT imaging indicates that the wetting front advances rapidly through larger pores, prompting swift pore collapse and cementation softening, thereby amplifying deformation. In contrast, remolded loess shows a diffuse wetting front and gradual collapse owing to its homogeneous fine-pore structure. Confining pressure affects collapse behavior through short-term suppression and long-term promotion. Using CT data, structural parameters are defined and a damage evolution equation for loess collapse deformation is proposed, considering the influence of confining pressure and saturation increments on collapse damage.