The present invention relates to the field of display technologies, and provides an array substrate, a manufacturing method thereof, and a display device. The array substrate includes a first electrode layer. The first electrode layer may include an indium tin oxide layer and a planarization layer. The indium tin oxide layer is disposed on a substrate and includes indium tin oxide particles; the planarization layer is disposed on a side of the indium tin oxide layer away from the substrate, and fills at least part of gaps between the indium tin oxide particles, and the planarization layer can conduct electricity.