Abstract: For a 600 MW wet-cooled unit of a power plant in Hebei province, ANSYS Fluent software was used to numerically simulate the flow field of the steam turbine exhaust passage. It was found that under the original design, due to the axial exhaust steam of the exhaust cylinder and the diffusion angle of the condenser neck, a large low-speed vortex area appeared in the exhaust steam passage, which had a negative effect on the heat transfer performance of the condenser. The exhaust steam of the feed water pump steam turbine had a certain supplementary effect on the low-speed vortex area and could improve the flow field to a certain extent. Aiming at this phenomenon, the exhaust passage flow field was optimized through the design of diversion structures. The results show that after optimizing the flow field, the crew exhaust steam condensed in the main area of the upper tube bundle planar velocity uniformity has been significantly increased, which is benefit to improve the condenser heat transfer coefficient, reduce the unit back pressure, and promote the efficiency of generating units.