PLC is also good for display, keyboard circuit and alarm circuit to control, make the medical staff can easily modify change speed, at the same time able to timely processing in encountered in the process of change of the iv plug or produce the problem such as air bubbles. Purging instrument application helps to reduce health care work intensity, improve the safety, accuracy and work efficiency, and improve the nursing level. This system structure is small, the quality is light, easy to carry, suitable for prehospital emergency treatment, the hospital general ward and family ward and field first aid.