The present invention relates to the field of display technology, and discloses an array substrate, a manufacturing method thereof and a display device, for reducing the light leakage of a display device. The array substrate comprises a plurality of pixel regions arranged in arrays on a base substrate, two adjacent ones of the pixel regions having a signal line arranged therebetween, and the pixel regions and the signal line having a gap therebetween, wherein the array substrate further comprises at least one light-leakage-proof electrode arranged to be insulated from the pixel regions and the signal line, and the vertical projection of the light-leakage-proof electrode on the base substrate at least covers a portion of the vertical projection of the gap on the base substrate. The present invention is applicable in the field of display technology.