The process flow of the indirect air cooling system is: circulating water enters the water side of the surface condenser through the surface heat exchange to cool the steam turbine exhaust on the steam side of the condenser, and the heated circulating water is pumped by the circulating water to the air cooling tower and dissipates heat through air cooling The surface heat exchange between the condenser and the air, the circulating water is cooled by the air, and then returns to the condenser to cool the exhaust steam of the turbine, forming a sealed cycle.