The invention provides an array substrate and a manufacturing method thereof as well as a display device. A transparent conductive layer in a thin film transistor connection area is in direct contact with a grid lead wire, an ohm contact layer, source electrode and drain electrode lead-out wires and a substrate by etching a grid insulating layer and an active semiconductor layer of the thin film transistor connection area in a GOA (Global Outstanding Assessment) area, so that the condition that the transparent conductive layer of the thin film transistor connection area cracks can be reduced; and an insulating stopping layer is additionally arranged between the ohm contact layer and the active semiconductor layer in an area in which a thin film transistor in the GOA area is located, so that a channel of the thin film transistor is prevented from breaking.