An organic light-emitting diode (OLED) display panel and a manufacturing method thereof are provided. The OLED display panel includes a folding region and a non-folding region. The folding region includes a first flexible layer, an inorganic layer, a second flexible layer, a buffer layer, a metal wiring layer, a planarization layer, and a pixel defining layer, which are sequentially stacked. A side of the buffer layer opposite to the second flexible layer is provided with holes, and each of the holes is deposited with a first organic filling layer. The metal wiring layer covers a side of the buffer layer and the first organic filling layer, and a cross section of the first organic filling layer of the folding region is formed with a zigzag shape.