Embodiments of the present application provide an Oxide TFT, a manufacturing method thereof, an array substrate and a display device. The Oxide TFT includes a base substrate; a gate electrode, a gate insulating layer and an active layer which are located on the base substrate; a source electrode and a drain electrode, the active layer is at least partly covered with the source electrode and the drain electrode; and a channel protection layer located between the source electrode and the drain electrode, each of the source electrode and the drain electrode includes at least part of a first metallic layer and at least part of a second metallic layer, the first metallic and the second metallic layer are stacked one on another, the channel protection layer is of a metal oxide.