Abstract: The water storage operation of Baihetan Reservoir leads to a large number of landslide deformations, but there is a lack of systematic research on the sensitivity of landslide deformation to reservoir water level changes. Through InSAR deformation monitoring technology, optical remote sensing, field survey statistics and Spearman correlation coefficient analysis, the results show that: 47 wading deformation landslides were investigated. The surface deformation rates, observed from January 2019 to December 2023, range from −57.29 mm/year to 58.52 mm/year. The Spearman correlation coefficient between the monthly average displacement of landslides and the fluctuation amplitude of the reservoir water level indicates a moderate correlation. Reservoir water level fluctuations are the primary drivers of landslide deformation, while only a few landslides are significantly influenced by rainfall. The sensitivity of landslide deformation to reservoir water level changes, in descending order, is as follows: frequency of reservoir water level fluctuations, magnitude of reservoir water level decrease, and magnitude of reservoir water level increase. Specifically, 26 landslides are sensitive to the frequency of reservoir water level fluctuations, accounting for 55.32% of all Wading landslides; 14 landslides are sensitive to the magnitude of reservoir water level decrease, accounting for 29.79%; and 7 landslides are sensitive to the magnitude of reservoir water level increase, accounting for 14.89%. The research results can provide a scientific basis for the prevention of landslide disasters in large reservoirs.