Wind Towers are small towers, which have been used for the natural ventilation of the buildings in hot, arid regions of Iran since many years ago. When the wind blows, air enters the channel of wind tower, it transfers the heat to the internal surface of wind tower walls and finally the cool air comes into the building. The most important advantage of wind towers is air conditioning and air cooling without any use of electrical energy. In this study, the performance of the tallest wind tower of the world (wind tower of Dolatabad garden in city of Yazd) is analyzed by employing a CFD package. The temperature, perasure and velocity disturbutions of air at different crosssections and along the column of wind tower are investigated. Heat transfer, fluid mechanics and thermodynamics principles are applied in order to evaluate the performance of wind towers. Finally, the results are presented.