Aiming at the problems of low production efficiency and error-prone quantity of plastic expansion tube manual packaging, this paper proposes a plastic expansion tube automatic packaging device based on programmable logic controller (PLC) and air pressure control technology. According to the needs of the development function, it proposes the automatic supply plan of the expansion tube, the automatic supply plan of the plastic film, the heat sealing and cutting plan of the packaging bag, the drawing plan of the packaging bag, and the air bag squeezing plan. According to the principle of the production process, it realizes the design of the electrical schematic diagram and the main part of the control software. It’s suitable for different packaging specifications through HMI parameter setting. Compared with manual operation, the production efficiency is increased by 4 times, the quantity is accurate, the labor intensity of personnel is small, and the space taken up after packaging is small. Practice shows that this equipment has obvious advantages over manual methods in terms of production efficiency, labor intensity, and quantity accuracy, and has broad application prospects in small plastic packaging.