Automatic shrinkage packaging machine is an automatic packaging equipment which combines pneumatic components with mechanical devices and is controlled by PLC and other peripheral circuits. The execution element of the device is the cylinder. A two position five way solenoid valve controls its forward and backward motion. The working position of the cylinder is detected by magnetic switch and proximity switch and fed back to PLC. The PLC sends out control commands to the electromagnetic valve of the corresponding cylinder through the program to control the action of the cylinder.