Abstract: Based on the prototype observation data, numerical simulation and physical model test results of atomization caused by the flood discharging of typical high arch dams, we analyze the atomization law of the high arch dams when the flood discharging outlets (tunnels) are partially open, and probe into the ways to minigate the hazards caused by the atomization through flood discharge dispatching, so as to ensure the safe and effective operation of the hydro-power stations. The analysis results show that the distribution of atomized rain area generated by the crest outlets or bottom (mid-level) outlets flood discharging is closely related to the flow inflowing velocity, and the area and angle of the downstream water jet, and the influences of the inflowing velocity on the distribution of the atomized rain area given by the bottom (mid-level) outlets flood discharging are more obvious. When the reservoir water level and discharge amount are constant, the atomized rainfall intensity and its influence range of the flood discharging tunnel operation are the smallest, and the atomization influence area is concentrated in the lower reaches far from the dam body, while the atomized rainfall intensity and its influence range caused by the bottom (mid-level) outlets flood discharge are significantly larger than those of the crest outlet flood discharge or spillway tunnel operation. The analysis results can provide references for the reasonable flood discharge dispatching of high arch dam projects.