<p>Landslide‑induced wave (LIW) hazards generated by fluctuations in reservoir water levels have the potential to pose a significant risk to dam safety, reservoir navigation and the lives of residents. The RS deposit landslide located on the left bank of the RM dam reservoir, China, approximately 5.4 km away from the dam, has an overall volume of approximately 4700 × 10⁴ m³, and there is a risk of waves caused by landslide instability. To reveal the formation and propagation of LIWs, in this study, the potential landslide instability modes of the RS deposit induced by reservoir water level changes were initially elucidated. A 3D numerical simulation method was subsequently employed using FLOW-3D to analyze the potential influence of wave action and forecast the attributes of impulse waves, as well as their propagation dynamics, resulting from the comprehensive instability of the deposit under a high water level during construction at 2863.8 m and a normal storage level at 2895 m. The results indicate that under both water level conditions, the maximum wave run-up height at the dam does not reach the dam crest, demonstrating a certain level of safety margin for the dam. Additionally, the maximum impact pressure of the waves on the dam is 0.161 MPa at the still water surface level of 2863.8 m. Given the danger and uncertainty of LIW hazards, continuous and close monitoring is necessary. It is also recommended that the height of the wave walls be increased to protect inhabitants living downstream of the dam and critical infrastructure from LIWs. The present study provides valuable insights for research on large deposit landslides in reservoir areas and landslide disaster chains in similar regions worldwide.</p>