A flexible organic light emitting diode (OLED) panel is provided. The flexible OLED panel includes a flexible substrate including a light emitting region, a thinned region, and a wiring region, wherein the light emitting region is adjacent to the wiring region, the thinned region is disposed between the light emitting region and the wiring region, and the thinned region includes: a substrate groove; and a first ductile material disposed in the substrate; a plurality of metal wires disposed on the light emitting region and the wiring region of the flexible substrate; a light emitting layer disposed on one of the metal wires, and the light emitting layer located in the light emitting region; and an encapsulation layer disposed on the light emitting layer, and the encapsulation layer including an encapsulation-layer groove located in the thinned region, wherein the encapsulation-layer groove is opposite to the substrate groove.