In this study, a temperature control system was designed based on an infrared thermal image of a hydroelectric hybrid cooling tower. A theoretical model of a cooling tower thermal calculation was deduced based on the structural characteristics of a hydroelectric hybrid cooling tower, as well as the balance equation of heat and mass exchange in a cooling tower and the Merkel mathematical model. A thermal performance monitoring model of a countercurrent cooling tower was first developed using infrared thermal imaging technology, and then the temperature control system for a cooling tower was designed.The causes of temperature control precision errors in the cooling tower temperature control system were analyzed. The accuracy of the thermal calculation model and the feasibility of using a hand-held infrared thermometer for designing the temperature control system of a cooling tower were verified by field experiments.