Abstract: Based on the wall-film model, the generation condition of liquid film formation in none-hooked wave-plate steam separator was studied by three-dimensional numerical simulation. The Realizable k-ε model and wall-film model were applied in the simulation. According to the simulation results, the separation efficiency was analyzed．The results show that the wall formation liquid film area and the height increase with inlet velocity or droplet diameter, if the structure of wave-plate isn’t changed and a second premise isn’t considered, so the separation efficiency is improved. When the inlet velocity and droplet diameter are fixed, the liquid film height and the area increase firstly and then decrease with the increase of the steam humidity. When the humidity is 10%, the area and height are the maximum value, and the separation efficiency is best.