A cooling stage for the heat treatment process was optimized in order to solve the problem of nonuniformity of the outlet wind speed based on computational fluid dynamics (CFD). After the numerical simulation of cooling stage wind field, some coefficient of speed, including maximum wind velocity, minimum wind velocity, average wind velocity and standard deviation of wind velocity were obtained, which were based on some working conditions, as the cooling stage without windshields and with windshields of different heights and angles. According to the optimization results the impact of height and angle on wind speed uniformity was analyzed to obtain the optimal height and angle of the windshields. The results show that the windshields set in the wind tunnel are conducive to improve the outlet wind uniformity, and the height of which has the most significant impact, and then the angle.