The invention relates to the technical field of display, and displays an array substrate, a preparation method thereof, a display panel and a display device. The array substrate comprises an underlayer substrate, a pixel circuit layer, a flat layer and a plurality of anodes, wherein the pixel circuit layer is arranged on the underlayer substrate; the flat layer is arranged on the pixel circuit layer, and the flat layer is provided with a plurality of grooves which are in one-to-correspondence with pixel light-emitting areas; and the anodes; and the plurality of anodes are respectively arrangedin the grooves of the flat layer and electrically connected with the pixel circuit layer. According to the array substrate, the anodes are arranged in the grooves of the flat layer, the edges of theanodes can be effectively prevented from being damaged to form foreign matters and warping during the preparation process of the anodes, thereby being capable of preventing the anodes from damaging afilm layer on the anodes to result in a short circuit with the cathode, and effectively avoiding the phenomena of poor dark spots and dark pixels of pixels.