Embodiments of the present disclosure provide an OLED substrate and a manufacturing method thereof and a display device. The OLED substrate includes: a base substrate; a first electrode and a second electrode which are on the base substrate; an organic material functional layer between the first electrode and the second electrode; and an auxiliary heat dissipation layer which is at a light exit side of the organic material functional layer and is in contact with the organic material functional layer. The auxiliary heat dissipation layer includes a metal heat dissipation portion and a metal oxide light transmission portion.