A thin film transistor, an array substrate and a manufacturing method of the thin film transistor are provided, the thin film transistor includes a base substrate; and a first active layer, a first insulating layer and a second active layer, which are sequentially arranged on the base substrate, the first active layer is in contact with the second active layer through a first via hole structure located in the first insulating layer, and non-contacted portions of the first active layer and the second active layer are separated by the first insulating layer, the thin film transistor has a plurality of active layer structures, so that the charges are gathered on two surfaces of each of the active layers, and the number of the charges gathered on the surfaces of the active layers is multiplied, and the open state current of the thin film transistor is multiplied.