Abstract: The physical model test is the main way of studying the problems of the flood discharge-induced atomization, but the model of the flood discharge-induced atomization has obvious scale effect. In order to improve the conversion accuracy of model rainfall intensity and reduce the influences of scale effect of the atomization model, based on the prototype observation and model test data of the flood discharge-induced atomized rainfall intensity of the Ankang, Wujiangdu, Ertan, Baishan and other hydropower stations, the similarity scale of the flood discharge-induced atomized rainfall model is classified according to the flood discharge modes and energy dissipator shapes. The relationships between the index n (Sr=Lrⁿ), geometric scale (Lr) and Weber number (We) are analyzed using different classification methods. The research results show that the relationships between the rainfall intensity given by the flood discharge-inuced atomization model and the prototype rainfall intensity don't change in accordance with the same scale index law. The values of index n are related to the shape of the energy dissipators, flood discharge modes, geometric scales and the flow Weber number. However, the larger the model scale and the flow Weber number are, the smaller the scale effect of the atomization model is, and the smaller the value of index n is whether the flood discharges through the crest outlets, or the mid-level (deep) outlets, or the flood discharging tunnels.