An array substrate, a manufacturing method thereof and a display device are disclosed. The array substrate comprises a gate electrode layer, an active layer and a source-drain electrode layer that are disposed on a substrate. The substrate comprises a storage capacitance region thereon II. In the storage capacitance region II, projections of the gate electrode layer and the active layer on the substrate are at least partially overlapped, and projections of the active layer and the source-drain electrode layer on the substrate are at least partially overlapped. The array substrate can effectively increase the storage capacitance without increasing an area occupied by the storage capacitance region, which is advantageously to reduce a pixel area and increase PPI.