The work aims to propose a fuzzy PID weighing control system based on PLC to solve the problem of non-linearity and time variability in the weighing control system of bag-delivering packaging machine due to the vibration of materials and electromagnetic vibrating feeders. Based on the characteristics of PLC, a fuzzy PID control method based on PLC was designed. Weighing error and error change rate were used as system inputs. Siemens S7-200 series PLC was used to analyze and design the implementation of fuzzy PID control strategy for the weighing system and realize real-time change of three PID parameters. The control system was simulated and analyzed based on Matlab, and the control effect was verified through online operation. The measurement deviation of the weighing system of the bag-delivering packaging machine was less than 0.5%, and the simulation results showed that the fuzzy PID control effect was better than the traditional PID control effect. The fuzzy PID control system of the packaging machine weighing system based on PLC has stable actual control and strong robustness, which improves the stability and weighing accuracy of the packaging machine weighing process; and its precision control is about 0.5%.