Abstract: Based on traditional PID control and fuzzy control technologies, this paper designs an adaptive fuzzy-PID controller by absorbing the advantages of both, and applies it to pressure control. The adaptive fuzzy-PID pressure control system based on an S7-200 PLC uses deviation and deviation change rate as inputs. According to the requirements of different operating conditions of the controlled system, satisfactory dynamic and static control performance is obtained by modifying the parameters of the PID controller. Keywords: Fuzzy control; Adaptive PID; PLC Abstract: The self-adaptive Fuzzy-PID controller is designed based on traditional PID control technology and fuzzy control technology and is applied to a pressure control system. A self-adaptive Fuzzy-PID control system based on an S7-200 PLC is implemented. It takes the deviation and the deviation change as input, and adjusts the parameters of the PID controller according to the varying performance state to achieve good dynamic and static control quality. Keywords: Fuzzy control; adaptive; PID; PLC 1. Introduction Conventional PID controllers are widely used in industrial control due to their mature technology. They are characterized by high control accuracy but poor robustness, and are difficult to achieve satisfactory control effects for nonlinear and time-varying parameter systems. Fuzzy control is a new type of intelligent control algorithm based on fuzzy language sets, fuzzy variables, and fuzzy inference. Its characteristics include not needing to know the precise mathematical model of the controlled system and strong control performance robustness. However, single fuzzy control often fails to meet the system's control accuracy requirements. This paper combines PID control and fuzzy control techniques to design an adaptive fuzzy-PID controller. Operational results show that it exhibits good control performance. For details, please click: PLC-based Adaptive Fuzzy-PID Pressure Control System