The embodiments of the present invention disclose an array substrate and manufacturing method thereof, and a display device. The array substrate provided in an embodiment of the present invention comprises: a substrate, and a gate metal layer, an active layer and a source/drain metal layer formed on the substrate; wherein, on at least one side of the gate metal layer, there is formed an isolation buffer layer, and/or, on at least one side of the source/drain metal layer, there is formed an isolation buffer layer; furthermore, the isolation buffer layer is made of molybdenum oxide.