Because the accuracy control of fully automatic weighing and packaging is easily affected by the impact of materials and other factors, it is difficult to keep the accuracy control stable and reduce its anti-interference performance. Therefore, the control method of fully automatic weighing and packaging accuracy based on PLC redundancy technology is proposed. Establish the mathematical model of the load cell, use the moving average filter and program judgment filter to process the weighing original signal, remove the dynamic oscillation and interference factors, use the processed signal as the input data, use the PLC redundancy technology to develop a synchronization mechanism to realize the synchronous transmission of data transmission and control commands. On this basis, the designed expert controller is used to realize the precision control of fully automatic weighing and packaging according to a flexible control rule library. The designed fully automatic weighing and packaging accuracy control method based on PLC redundancy technology has small cross-code weight measurement deviation and good communication data coordination. The anti-interference performance of the control system can be effectively improved by the control method of filter processing.