High-dam flood discharge, a critical phase in hydropower engineering, has increasingly attracted attention due to ground vibration issues. This vibration typically appears as a continuous, low-frequency, low-amplitude oscillation, which is difficult to mitigate using traditional vibration reduction methods such as dampers or rubber shock absorbers. Using the RM project as an example, this research combined numerical simulations and hydraulic model experiments to analyze the effects of discharge and flood discharge scheduling on ground vibration. The results showed that multi-hole and balanced discharge openings significantly improved water flow patterns, dramatically reducing pulsation loads in the water cushion basin: the bottom plate’s maximum pulsation pressure decreased by 27%–82%, with an overall pressure reduction of 12%–45%, while side walls experienced a maximum pulsation pressure drop of 47%–62% and an overall pressure reduction of 35%–60%. The flood discharge vibration response decreased by approximately 45%, with the multi-hole balanced discharge method proving highly effective in controlling ground vibration. By optimizing discharge scheduling methods, the research effectively reduced ground vibration response, thereby enhancing the safety of surrounding residents.