The present invention provides an OLED substrate and a manufacture method thereof. In the manufacture method of the OLED substrate of the present invention, by utilizing the inorganic material to manufacture the pixel definition layer, it can reduce the risk that pixel definition layer is wrong stripped in the photoresist stripping process, and meanwhile, reduce the risk that the fine metal mask is polluted in the evaporation process to raise the usage efficiency of the fine metal mask. The OLED substrate of the present invention is manufactured by the aforesaid manufacture method of the OLED substrate. The structure of the pixel definition layer is complete, and can effectively protect the anodes and the substrate thereunder, and the element performance is good.