The invention discloses an array substrate and a manufacturing method thereof, and a display device. Therefore, the process steps are reduced, so that the production cost is lowered and the production efficiency is improved. The array substrate includes a substrate base plate, thin-film transistors arranged on the substrate base plate, data lines connected with source electrodes/drain electrodes of all thin-film transistors, and a light shield layer arranged on the substrate base plate. The data lines and the light shield layer are arranged at the same layer. First via holes are formed above the data lines to expose parts of data lines. The thin-film transistors include semiconductor active layers and first transparent electrodes; second via holes are formed above the semiconductor active layers to expose parts of the semiconductor active layers; and the data lines and the semiconductor active layers are electrically connected by the first transparent electrodes through the first via holes and the second via holes.