With the speed growth of petroleum engineering, the requirements for the temperature control performance of petroleum heat transfer oil boilers are becoming higher. Traditional temperature control systems have problems such as poor temperature control accuracy. To address these issues, a temperature control system for petroleum heat transfer oil boilers based on microprocessors and proportional‐integral‐derivative is designed. The research first studies the fuzzy proportional‐integral‐derivative control system, and then combines it with a microprocessor to design a new temperature control system. Finally, experiments and practical applications are used to assess the effectiveness of the temperature control system. The results denote that in the simulation experiment, the temperature recognition accuracy of the microprocessor proportional‐integral‐derivative system is 93.26%. At the same time, the system increases the temperature of the oil outlet to around 100°C after about 4 min of boiler operation, and maintains the stable temperature of the oil outlet continuously. In the study of overshoot, the average overshoot value of the system is 10.03%, and the average steady‐state error value is 3.71%. These verification indicators are superior to the comparative control system, indicating that the fuzzy control proportional‐integral‐derivative temperature control system based on microprocessors has good effects in the application of petroleum heat transfer oil boilers. Through this system, the stability and control accuracy of boiler temperature can be improved, and intelligent control of the boiler can be achieved. This is of great meaning for raising the energy and work efficiency of boilers, and reducing energy waste.