The centrifuge experiment was conducted to investigate the impact of weak interlayer reservoir bank slope water level rise on slope stability. The analysis of the experimental data revealed that the collapse of the reservoir bank slope was primarily caused by the rapid rise in water level in the reservoir, leading to increased infiltration along the slope. This process resulted in the weakening of the interlayer strength and the reduction in the strength of the reservoir bank slope soil body. Consequently, transverse cracks began to form at the foot of the slope, which expanded and eventually led to segmental slope collapse. Concurrently, the correlation between soil water content and physical strength index was determined through conducting direct shear experiments on test soils with varying water contents. This correlation was integrated into a numerical model to predict the sliding surface of the slope soil. The numerical model was validated using centrifuge model experiments. The outcomes of these experiments demonstrated that the circular sliding surface generated by the calculations was largely consistent with that observed in centrifugal experiments. Ultimately, a detailed finite element model was developed to simulate the relationship between the safety factor of the bank slope and the height of water level rise, on the basis of the physical model. This study can provide a scientific reference for the study of the collapse mechanism of the bank slope due to the rise of water level.