Composite PET soft film and preparation method thereof

The invention relates to a composite PET soft film and a preparation method thereof. The preparation method of the composite PET soft film comprises the steps that a mother board is coated with photoetching mold glue, the photoetching mold glue covers and is higher than a graphic structure, a photoresist layer is formed, and the area of the graphic structure is larger than or equal to three fifths of the area of the mother board; the PET soft film is divided into more than two pattern transfer areas; a light-transmitting area is arranged on the ultraviolet-proof film; the pattern transfer area, the light-transmitting area and the pattern structure are sequentially aligned in the vertical direction, and the PET soft film and the photoresist layer are attached to each other at the position of the light-transmitting area; the PET soft film is vertically exposed to cure the photoresist layer in the light-transmitting area to form a transfer pattern structure; the PET soft film is demoulded; and the next pattern t