A photosensitive device, a manufacturing method thereof, a detection substrate and an array substrate are provided. The photosensitive device is formed on a substrate, and it includes a photosensitive element and a thin film transistor. The photosensitive element includes a first electrode layer on the substrate; a second electrode layer on a side of the first electrode layer distal to the substrate; and a photoelectric conversion layer between the first electrode layer and the second electrode layer. The thin film transistor is electrically connected to the photosensitive element, and it includes a first gate electrode on the substrate; an active layer on a side of the first gate electrode distal to the substrate; and a second gate electrode on a side of the active layer distal to the substrate. The first electrode layer and the second gate electrode are located in the same layer.