Abstract: The separation ability of AP1000 wave-type plate steam-water separator was studied numerically based on proposed droplet collision model. A wave-type plate with high separation efficiency and low flow resistance was designed by structure optimization. Firstly, the behavior of droplet was described mathematically by droplet collision model, and then the model was solved numerically. Secondly, the separation efficiency and equivalent moisture distribution of droplet with different droplet diameters and different inlet droplet volume fractions were obtained, by simulating the moving and colliding behaviors of droplet in a wave-type plate. Thirdly, through the modification design of the wave-type plate structure, the purpose of improving separation efficiency and reducing flow resistance was achieved. The numerical simulation method used in this paper has practical significance for the performance optimization of AP1000 wave-type plate steam-water separator.