The disclosure provides a thin film transistor and a fabricating method thereof, and an array substrate. The thin film transistor includes a gate, a first active layer, a second active layer, a first source, a first drain, a second source and a second drain which are provided above a base substrate. The first active layer is located at a side of the gate facing the base substrate, and the second active layer is located at a side of the gate facing away from the first active layer. The first source and the first drain are located at a side of the first active layer facing away from the gate and are connected with the first active layer. The second source and the second drain are located at a side of the second active layer facing away from the gate and are connected with the second active layer.