In the design of variable frequency speed control system of packaging machine, due to the influence of control mode, the energy consumption of the control system is high. The work aims to design a variable frequency speed control system of packaging machine based on PLC technology. In the hardware part, the programmable control box and the frequency converter were designed. In the software part, through the design of the inverter parameters, the normal operation of the frequency control system was ensured. Aiming at PLC technology, the PLC program needed in the control system was designed to achieve the effect of controlling the frequency conversion speed regulation of the packaging machine. Finally the output of PLC program was presented through touch screen. The design of variable frequency speed control system of packaging machine was completed.The experimental results showed that compared with the two traditional control systems, the energy consumption of the control system designed in this work was reduced by 49.5% and 39.2% respectively. The energy consumption of the control system is reduced, and the research has a good effect in practical application.