Abstract: The thermal performance of high-level water collecting cooling towers is significantly affected by environmental wind speed, and the adverse effects of crosswind can be partially mitigated by the installation of cross walls with appropriate angles and heights. Based on this, a high-level water collecting cooling tower of a 1 000 MW unit was taken as the research object. The influences of cross wall angles (30°, 45°, 90°) and heights (12 selected heights within 0-18.3 m) on the performance of the cooling tower under a typical local crosswind condition (wind speed v=5 m/s) were investigated through numerical simulation. Results indicate that more uniform airflow distribution is achieved by the 90° cross wall, and localized high-temperature zones are eliminated. A trend of rapid initial increase followed by stabilization is observed for the circulating water temperature drop with the increase of cross wall height. The optimal cooling performance is achieved when the height of the 90° cross wall is set at 14.3 m, at which the circulating water temperature drop and ventilation are reached at 10.26 K and 38 543.51 kg/s, respectively.