The invention discloses an array substrate and a preparation method thereof, and a display device, wherein the array substrate is used for reducing grain recognition light propagation paths and improving grain recognition accuracy and efficiency. The array substrate comprises: a substrate body; a display area and a peripheral area, wherein the display area comprises a first thin film transistor onthe substrate, a first connecting lead wore electrically connected with the first thin film transistor on the substrate, a packaging layer located on the first thin film transistor, a photosensitivedevice located on the packaging layer, and a second connecting lead wire located on the packaging layer and electrically connected with the photosensitive device, the first connecting lead wire, the second connecting lead wire and the packaging layer all extend to the peripheral area, the peripheral area comprises a retaining wall positioned between the first connecting lead wire and the packaginglayer, the packaging layer covers the retaining wall, the packaging layer is provided with a first via hole exposing the first connecting lead wire on the side, deviating from the first thin film transistor, of the retaining wall, and the second connecting lead wire is electrically connected with the first connecting lead wire through the first via hole.