Based on the similarity principle, a three-dimensional “unit pipe” physical model of a steam generator coupled quatrefoil tube support plate was established. A numerical study of the impacts of tube support plate on steam generator flow and heat transfer characteristics was performed by using the fluidsolid coupled methodology and thermal phase change model based on boundary conditions where the secondary side fluid run into the hot leg and cold leg by a distribution ratio of 4∶1. Simulation results show that balanced boiling distributions in the hot leg and cold leg are obtained and the calculated steam quality of the outlet agrees well with the operating parameter of the steam generator at the Daya Bay Nuclear Power Plant. Due to the smaller area of the flow crosssection of the tube support plate, the secondary fluid velocity, surface heat transfer coefficient and steam quality sharply increases and then decreases in the support regions, respectively. The recirculation behavior appears at the top of the support plate, which increases the possibility of deposit of particles and tube corrosion. This numerical simulation methodology can provide technical support for the optimization of the structural design of steam generator tube support plate.