Aiming at the problem that the influence range for flood discharge atomization is not easy to be directly modeled by mathematical models, flood discharge from a high dam power station was taken as a study object, in which a three-dimensional mathematical model was used to calculate the hydraulic characteristic values such as the flow velocity and the jet angle into water. The empirical formula of the prototype observation was used to predict the flooding atomization range, and a physical model test was used for verification analysis. The results show that, affected by the scale effect, the influence range of the physical model atomization test is smaller than the calculation range but with a similar variation trend. The fog flow is affected by inertia and water tongue wind, revealing a climbing movement along the water tongue axis, which is consistent with the prototype measurement. Affected by the ski-jump jet at the outlet, the flood discharge atomization effect is concentrated downstream of the water tongue drop point. The upstream and right banks of the plunge pool have a small rainfall intensity with a limited influence range.