Array substrate, display panel and preparation method of array substrate

The invention provides an array substrate, a display panel and a preparation method of the array substrate. The array substrate comprises a protective layer and a through hole and also comprises a first conducting layer, wherein the protective layer is formed on the substrate; the through hole penetrates through the protective layer; the first conducting layer is positioned on one side, far away from the substrate, of the protective layer with the through hole. The thickness of the first conducting layer at the bottom part of the through hole is more than that of the first conducting layer at the area beyond the through hole, namely, the thickness of the first conducting layer at the bottom part of the through hole is increased, and the section difference between the bottom of a middle hole and the top of the hole can be reduced, so that the risk of dropping of the first conducting film layer in the through hole is reduced, further the signal interruption of the electrodes is avoided and the electric connection performance of a TFT (Thin Film Transistor) is improved.