PET material for steel plastic strip equipment is widely used in the beverage packaging industry due to its excellent properties such as good transparency, easy stretchability, and various barrier properties. The various physical properties of PET plastic steel strip equipment are closely related to its viscosity, therefore, it is extremely necessary to study the viscosity changes of PET during processing. Qingdao Delma Plastic Machinery Co., Ltd. uses PET raw materials to produce various beverage packaging materials. However, due to the sensitivity of PET materials to moisture, the viscosity of PET often decreases. Therefore, studying the influence of moisture on viscosity during processing, controlling the moisture content during PET processing, and improving the quality of PET products are very beneficial.