Abstract: The details of the flow field in moisture separator reheater (MSR) on the actual operating conditions were studied and the influence of steam flow uniformity through the corrugated plate with two different orifice opening ways by a three-dimensional numerical simulation was compared. The standard k-ε turbulence model combined with the standard wall function was used to simulate the vapor phase field of the MSR based on CFD. The corrugated plate, the wave-plate and the tube bundle were modeled by the porous media model, and the opening ratio of the corrugated plate was adjusted by UDF. Impingement plate was simplified as the porous step boundary. The results show that the analysis results from CFD are consistent with the aerodynamic test results on absolute value and range ability. The uniformity of the steam velocity before the wave-plate is better when the non-uniform orifice opening way is used, which maintains the average porosity the same with the uniform way. And the total pressure drop of the steam through the corrugated plate and the separator is less than 14 kPa, which meets the requirements of the pressure loss design of MSR. The pressure drop of the reheater tube bundle is the largest in the whole streamline.