An array substrate is provided, including a substrate, a driver thin film transistor and a switch thin film transistor disposed on the substrate, the driver thin film transistor and the switch thin film transistor both include a gate, a gate insulating layer, an active layer, a source, and a drain. A barrier layer is disposed between the gate and the gate insulating layer of the driver thin film transistor. A manufacturing method thereof includes forming a barrier layer on the gate of the driver thin film transistor. Compared with existing arts, forming a barrier layer between the gate and the gate insulating layer of the driver thin film transistor to prevent its active layer from water and active oxygen ions affections can improve the electrical property and reliability of the thin film transistor, and ensure the normal operation for driving the driver thin film transistor of organic light emitting diode.