An organic light-emitting diode (OLED) display panel and a manufacturing method thereof are provided. The OLED display panel includes a substrate, a pixel defining layer, an organic light-emitting layer, and an organic encapsulating layer. The pixel defining layer is disposed on the substrate and includes a plurality of recessed regions and a plurality of grooves. The recessed regions communicate with each other through the grooves. The recessed regions and the grooves form a mesh structure. The mesh structure defines a plurality of pixel regions. The organic light-emitting layer is disposed on the pixel defining layer and the organic encapsulating layer is disposed on the organic light-emitting layer.