Ordinary PET is a crystalline polymer. After the PET film is stretched orientated, it will produce a greater degree of crystallization. If it is heat-sealed, it will shrink and deform, so ordinary PET film does not have heat-sealing performance. When PET film is used for commodity packaging, in order to solve its heat sealing problem, the method of combining BOPET film with PE film or CPP film is usually adopted, which limits the application of BOPET film to a certain extent. In order to solve the heat-sealing problem, by modifying the PET resin and adopting the A/B/C three-layer die head, a three-layer co-extruded heat-sealing PET film has been developed. This heat-sealing PET film Because one side is a heat-sealable layer, it can be directly heat-sealed, which is very convenient to use. Heat-sealing PET film can be widely used in various commodity packaging and card protection film fields.