The invention provides a preparation method of a folding display panel. The method comprises the following steps that two roulettes are prepared on a to-be-attached supporting plate, the roulettes divide the supporting plate into a first area, a second area and a third area, and the second area is located between the first area and the third area; the first area and the second area are sequentially attached on an OLED display screen through an attaching roller, and the third area is naturally attached on the OLED display screen, wherein the second area faces toward a bending area of the OLED display screen, and the third area faces toward an OLB area of the OLED display screen; and the second area is torn off. According to the preparation method of the folding display panel, when the supporting plate is attached to the OLED display screen, the OLB area of the OLED display screen can not be pressed by the attaching roller, and the abnormal display of the OLED display screen can not be caused.