Polyester is an important variety of synthetic fiber and the trade name of polyester fiber in China. It is a fiber-forming polymer, polyethylene terephthalate (PET), which is made of purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG) through esterification or transesterification and polycondensation, and is made into fibers through spinning and post-treatment. Polyester is widely used in making clothes and industrial products. Polyester has excellent setting performance. The flat, fluffy or pleated polyester yarn or fabric generated after setting can remain unchanged for a long time after repeated washing in use.