An array substrate and a manufacturing method thereof and a display device are provided. The array substrate includes a base substrate, a polarizer, a plurality of active elements, a first organic protective layer and a first inorganic protective layer. The polarizer is located on a first side of the base substrate; the plurality of active elements are arranged in an array form and provided on a second side of the base substrate opposite to the first side; the first organic protective layer is located on a side of the polarizer facing away from the base substrate and covers the polarizer; and the first inorganic protective layer is located on a side of the first organic protective layer facing away from the polarizer and covers the first organic protective layer.