In order to clarify the generation and propagation characteristics of landslide-generated waves in narrow reservoir areas, the influence of landslide impacting velocity on the wave characteristics and reservoir structure is investigated, taking the potential landslide No.1 in the Yangqu Reservoir as an example. The whole process of landslide generation, development and propagation is analyzed using a three-dimensional numerical model, which is then verified by a physical model with a proportional scale of 1∶200. The results show that the time line of the waves simulated by the three-dimensional numerical model agrees well with that by the physical model, and the wave heights measured at the generation location and in front of the dam are consistent with the simulation results. In narrow reservoirs, the height of the leading wave decreases with the increase of the velocity, and it is not necessarily the highest among the waves. No obvious damping is found for the leading wave during the propagation from the landslide to the dam, but it contributes little to the total overtopping volume, because the peak of the overtopping discharge appears much later than the leading wave, which is probably due to the multiple scattering of waves near the dam.