The invention provides an OLED display panel and a manufacturing method thereof. The display panel comprises the following parts of a substrate comprising a color film layer and a first transparent conductive layer, wherein the first transparent conductive layer comprises a first region and a second region, the first region corresponds to a region forming the color film layer, and the second region corresponds to a region forming a gate stack layer; a buffer layer covering the first transparent conductive layer; an active area comprising a first active area and a second active area, wherein the first active area is located above the first region, and the second active area is located above the second region; a gate stack layer located above the second active area; an interlayer dielectriclayer, a second transparent conductive layer, a planarization layer, a color film layer, a second buffer layer, an anode, a pixel defining layer and a light emitting structure.