The production of safe and economical energy is one of the most important issues in the industry of any country. A large amount of this energy is generated in power plants, which include different parts. Choosing the systems and power plants components are vital and important. One of these components is cooling system. Due to the problem of water scarcity in the country, as well as the increasing restrictions imposed by environmental regulations on pollution from wet systems, dry cooling systems are becoming more important. However, the performance of dry cooling towers is sensitive to weather conditions and seasonal winds. To ensure the economic and reliable performance of the units under wind conditions, it is important to optimize the structure of the tower. The height of the Heller tower under study is 123 meters, the base diameter of the tower is 104 meters and the height of the heat exchangers is 15 meters. In the present study, the finite volume method has been used to simulate the Heller dry cooling tower and due to the turbulent flow, the k-? turbulence model has been used. The behavior of the tower under cross winds was investigated and an external windbreak wall located in front of tower to reduce wind nagative effects.Three wall parameters including wall height, wall distance from the tower and also the length of the wall arch were examined in order to find suitable and optimal windbreak. Finally, it was found that the amount of heat transfer will increase by 14.635 percent with the most suitable windbreak wall (with an arc length of 134 meters, height 36 meters and a distance of 104 meters from the center of the tower) compared to the same conditions without windbreak wall. Also, return water temperature from the tower diminished by 0.895 ° C. Key word Dry cooling tower, Heller, Wind breaker wall, Heat dissipation, Wind effect