In order to solve the defects of relying on the engineering experience, difficult maintenance and reducing the efficiency of the turbine in the traditional layout scheme of the water supply cooler in the secondary circulation technology of the hydropower station, this paper proposes an optimization method for the layout scheme of tail water coolers based on computational fluid dynamics(CFD) through the steady-state numerical simulation of three-dimensional flow in the tailrace. By analyzing the spatial distribution characteristics of multiple physical quantities such as streamlines, flow velocity, turbulent kinetic energy and other physical quantities of the flow field in the area where the cooler is to be installed on the platform above the draft tube in the simulation results, the location with a higher flow velocity from the cooler is selected as the appropriate installation position. The three-dimensional flow domain of the complex tailrace channel considering the geometric model of the actual cooler is established for the numerical simulation and verification to check the rationality of the layout. The simulation and verification results show that this scheme not only meets the cooling requirements of the cooler, but also facilitates the maintenance and avoids any impact on the operation of the unit.