Abstarct: Natural draft dry cooling towers are the common towers that mostly used in waterless areas. The performance of dry-cooling towers is highly sensitive to the environment conditions, particularly the crosswind which may cause reduce up to 40% of the total power generation capacity. Therefore, understanding the environmental conditions effect on cooling tower performance is of great importance. In present thesis, a single cooling tower at the baxse in the ESLAMABBAD power station of IRAN experimentally and numerically studied. Experimental model made by ceramic. Pressure coefficient around model at the entrance of the towers has been measured by using wind tunnel. The effects of crosswinds on the thermal performance of natural draft dry cooling towers numerically and experimentally have been investigated. Using the finite volume method, the fluid flow and temperature distribution around and in a tower are simulated (Using FLUENT software). For modeling turbulent k-ε model was employed. Also the effects of external wind ribs are experimentally investigated. Finally, the effect of flue gas injection on natural draft cooling tower performance through experimental and numerical simulation has been studied. Results indicate that flue gas injection will improve the performance of cooling tower under cross wind condition. Another benefit from injection into a cooling tower is that the discharged flue gas gets thinned by as much as a factor of ten before throwing away to the atmosphere.