An OLED display panel and manufacturing method thereof. The OLED display panel includes a TFT array substrate, organic light emitting units, a first barrier, a second barrier, a trench, and a thin film packaging structure. The first barrier and the second barrier are disposed in a non-display region. The trench is formed corresponding to the position of a gap between the first barrier and the second barrier. The trench is disposed in an insulating layer stacked structure of the TFT array substrate. The thin film packaging structure covers above elements. The trench is disposed in a straight-edge region and a height difference is formed between the straight-edge region and a corner region. This can efficiently lower the risk of overflow from the corner region to the outside for an organic layer of the thin film packaging structure.