Compared with similar equipment, the three-layer coextrusion film blowing machine has the advantages of higher output, good product plasticization, low energy consumption and simple operation. It completely solves the problems of film ruffle and winding head, and improves the product quality to a new level. The produced film has high transparency, puncture resistance, high toughness, good low-temperature heat resistance, good composite fastness and anti crimping. This film can be widely used in light and heavy packaging because of its good barrier, fresh preservation, moisture resistance, frost resistance, oxygen resistance and oil resistance. After inspection, adjust the rotating speed of the inner, outer and middle main motors according to the requirements of the production task notice, and adjust the traction speed according to the thickness requirements. Turn on the rotation button to rotate the die head. The three-layer coextrusion heat shrinkable packaging film is processed by coextrusion blow molding process with linear low density polyethylene (LLDPE) and copolymerized polypropylene (TPP, PPC) as main raw materials and necessary additives. Its process is different from the traditional blow molding process. Due to the poor tensile properties of PP melt state, the traditional blow molding process cannot be used, but the double film bubble process is used, It is also called prandi process in the world.