An array substrate and a manufacturing method thereof, and a display device are provided. The manufacturing method of the array substrate includes forming a source-drain metal pattern on a substrate, wherein the substrate includes a display region and a peripheral region located around the display region, the source-drain metal pattern located on the peripheral region including a plurality of metal wires; and forming a protective structure on a lateral side of each of the metal wires, wherein the protective structure contacts and covers the lateral side of each of the metal wires.