Abstract: The effect of prevention measures on seven kinds of deflector under crosswind is simulated by CFD method. Based on the computational fluid dynamics method, and by ignoring the process of heat and mass transformation, the draft of the tower caused by hot steam is simulated by the boundary condition of fan. The resistance of tower and the ventilation rate of filling zone are simulated by porous medium boundary conditions, and the resistance of rain zone and the filling zone of the tower are calculated by the UDF source program. The rectifier effect of various types of deflector under different crosswind conditions and the quantitative analysis of the impact of crosswind on the flow field are obtained. The selection principle of crosswind defensive measures is presented so as to provide a theoretical basis for the selection of cooling tower deflector.