The invention provides a thin film transistor assembly, an array substrate and a display panel. The thin film transistor assembly comprise a first thin film transistor and a second thin film transistor which are arranged on a substrate. The first thin film transistor comprises a first source, a first drain and a first active layer. The second thin film transistor comprises a second source and a second drain. The first source is arranged on the side of the first active layer close to the substrate. The first drain is arranged on the side of the first active layer far away from the substrate. The second source and the second drain are arranged in the same layer as the first drain, and the orthographic projection of the first source e on the substrate and the orthographic projection of the second source on the substrate have an overlapping region. Therefore, the thin film transistor assembly can greatly reduce the flat area occupation of the thin film transistor assembly so that the areaof the black matrix shielding the thin film transistor can be effectively reduced when the thin film transistor assembly is applied to the display panel and the aperture ratio of the display panel canbe further improved, i.e. the light transmittance of the display panel can be improved and thus the display brightness of the display panel can be improved.