In order to overcome the problems of low efficiency and high control error of single channel to multi-channel in food packaging line, a multi-channel to single channel control method for food packaging line based on PLC was proposed. This method uses PROFINET industrial Ethernet technology to design the network architecture of the control system. The machines and equipment are connected through the packaging and conveying chain, the basic speed of the packaging chain is calculated, the production task is coordinated, the frequency signal and speed signal of the frequency converter are converted, and the adjustment test is carried out in the later stage to achieve the predicted control effect. The experimental results show that the packaging efficiency is always above 96%, and the minimum control error is 0.002, which has good control effect and can meet the production requirements of food packaging plants.