OLED display panel and preparation method thereof

The invention discloses an OLED display panel and a preparation method thereof, and belongs to the technical field of display. The OLED display panel comprises a substrate, a thin film transistor layer, a passivation layer, a light-emitting layer and a packaging layer which are sequentially arranged in a stacked mode, wherein the thin film transistor layer comprises a plurality of thin film transistors, wherein each thin film transistor comprises an oxide semiconductor layer. The OLED display panel further comprises a blocking layer; the blocking layer is arranged between the light-emitting layer and the passivation layer, and the blocking layer is used for blocking hydrogen generated by the packaging layer from being transferred to the oxide semiconductor layer. Through the arrangement of the blocking layer, the hydrogen generated by the packaging layer is prevented from being transferred to the oxide semiconductor layer, so that the situation that oxygen vacancies of the oxide semiconductor layer are conduc