A CFD simulation method for a batch cooling or heating mixing tank, which follows a specific controlled program, was developed in this study. The momentum transfer and turbulen heat transfer in the whole tank were included in the computation while the wall temperature was reset according to time. The simulation results show that the average temperature in the tank adheres to a specified cooling curve, but the temperature distribution can be ignored in a 10-liter mixing tank. The simulation results were verified with batch cooling experiments performed on pure water. Furthermore, the temperature distribution in a large-scale 5-m3 tank and the application of the temperature distribution in other chemical processes in the mixing tank is briefly discussed here.