Abstract: Taking the 2×350 MW air cooling unit as the research object,the numerical simulation method is adopted to study flow heat transfer characteristics of different tower air cooling systems under different ambient wind speeds in detail.The distribution of heat transfer on the water side and water temperature at the outlet of the air-cooling radiator under different tower types is revealed from two levels of the whole system and the local sector. The results show that the flow heat transfer performance of different indirect air cooling systems decreases with the increase of ambient wind speed;the cooling performance of hyperbolic towers is better than that of all straight conical towers in absence of wind;the cooling performance of the straight conical tower with a cone-segment ratio of 0.2 is lower than that of other tower structures at various ambient wind speeds. When the ambient wind speed is 4 m/s,the cooling performance of the straight conical tower with a cone-segment ratio of 0.5 is better than that of other tower structures,which also presents excellent performance at ambient wind speeds of 8 m/s and 12 m/s. This study can provide theoretical support for structural selection and design of indirect air cooling system of steel structure.