Abstract: To address the large temperature lag and inertia during aluminum foil annealing, a fuzzy PID parameter self-tuning control algorithm based on an S7-300 PLC is proposed. This paper utilizes the pointer addressing lookup table method in STEP7 to implement online lookup functionality, simplifying the control algorithm. Results show that the system exhibits high stability, control accuracy, and quality. Keywords: PID control, fuzzy parameter self-tuning, PLC, STEP7 In recent years, fuzzy control has been widely applied in China. However, in the field of fuzzy control applications, fuzzy controllers are primarily implemented using personal computers, microcontrollers, or dedicated fuzzy control chips. The implementation of fuzzy control on PLCs is basically divided into two types: one is through dedicated hardware, which is expensive and requires dedicated programming equipment, resulting in poor versatility; the other, more commonly used method, is software implementation, where the fuzzy control program is treated as a subroutine of the overall PLC control program, including data reading, fuzzy inference, and control signal output, with fuzzy control completed through interrupt calls to the subroutine. Currently, temperature control is mostly achieved using PID control. This method is simple and easy to implement, but parameter tuning is difficult. In practice, we often manually set PID parameters based on experience, and a set of tuned parameters cannot fully adapt to different annealing process requirements, and is also prone to large overshoot. This study addresses the slow heating rate, large overshoot, and low control accuracy that occur during the annealing process. Using the PLC programming software SIEMATIC STEP7 5.0, a modular programming method is adopted, and a fuzzy control algorithm is implemented using ladder diagrams and statement lists. Fuzzy parameters in the standard PID control module FB41 are self-tuned to achieve good control effect and good stability. 1. Basic Structure of the Temperature Control System for Aluminum Foil Annealing Furnace The temperature control system mainly consists of an S7-300 PLC and a TP270-10 human-machine interface. The human-machine interface completes intelligent background management, setting of various annealing parameters, and monitoring and alarming of the annealing status. The PLC, composed of a CPU315, digital input module SM321, digital output module SM322, analog input module SM331, and analog output module SM332, mainly performs the acquisition of various signals, processing of set parameters, control of various motors, and temperature control in the system. Research on a PLC-based fuzzy parameter self-tuning temperature control system.