Changing the air-cooling flow in air cooling unit, can improve heat transfer performance of air-cooling condenser, which has great significance in operation level of air-cooling unit. Physical model of deflector鈥檚 installed in air-cooling condenser for 600 MW unit was established. Using CFD software, numerical simulation was conducted by using simple algorithm and RNG k-e model in order to obtain the temperature and velocity field before and after installation of deflector within the air-cooling condenser in different wind speed, then the variation of air flow in the air-cooling condenser unit was analyzed. The result indicates that installation of deflector could make a better air flow, improve the effect of heat transfer and provide a optimal operation for the air-cooling system.