An array substrate including: a base substrate and a thin film transistor unit provided on the base substrate; the thin film transistor unit comprises: a first gate electrode provided on the base substrate, a gate insulating layer provided on the first gate electrode, a source electrode disposed in a same layer as the first gate electrode, an active layer provided on the source electrode, a drain electrode provided on the active layer, and the gate insulating layer disposed between the first gate electrode and the source electrode. This array substrate reduces a channel length of a conducting channel of the thin film transistor unit, and meanwhile increases an aperture ratio of a pixel.