<p>Landslides in reservoir areas pose significant risks, yet current research lacks comprehensive insights into their dynamic response mechanisms under fluctuating water levels. This study addresses this gap by conducting two sets of physical model tests under normal gravity, monitoring pore water pressure, soil pressure, displacement, and deformation fields within the landslide. The mechanical mechanisms of buoyancy-driven and seepage-driven landslides were analyzed, yielding key findings: The two most unstable stages of a landslide occur during high-water levels and the falling stage. At high-water levels, buoyancy significantly reduces the anti-sliding force. During the falling stage, residual buoyancy and increased outward seepage force exacerbate the sliding force, triggering landslides. The permeability of the sliding mass significantly affects its deformation response. Landslides with higher permeability coefficients tend to initiate sliding at high-water levels, while those with lower permeability coefficients typically initiate sliding during the falling stage, often resulting in retrogressive failure. Soil pressure in the sliding zone often indicates the unstable state of a landslide earlier than displacement monitoring results, suggesting that soil pressure could be a reliable criterion for predicting imminent landslides. Overall, this study effectively analyzed the occurrence, development, and evolution of buoyancy-driven and seepage-driven landslides using physical model experiments, validated the mechanical response characteristics of buoyancy-driven and seepage-driven landslides. It provides valuable experimental references for understanding the dynamic characteristics and mechanisms of reservoir landslides, contributing to more effective prediction and prevention strategies.</p>