Hydraulic turbine band castings are susceptible to deformation in heat treatment process if their cooling is not well controlled. The coupled analysis of forced air flow and heat transfer in normalizing process of a heavy turbine band runner casting with outer diameter of 8000 mm was carried out by using ANSYS software. The band undergoes significant deformation because of uneven cooling resulted by uneven air flow around it during normalizing. The forced air flow pattern is a key factor which influences the cooling uniformity and efficiency. It is optimized by adjusting the cooling fans’ orientation relative to the casting to form cyclone around it. Consequently, cooling uniformity is improved to avoid deformation.