The embodiment of the invention discloses an array substrate, a manufacturing method thereof and a display panel. The array substrate comprises a substrate, and a first planarization layer, a first conductive layer and a second planarization layer which are positioned on the substrate. The first planarization layer is located between the substrate and the second planarization layer; the first conductive layer is located between the first planarization layer and the second planarization layer; a first groove is formed in one side, close to the second planarization layer, of the first planarization layer; the first conductive layer is partially or completely located in the first groove, so that the flatness of the side, away from the substrate, of the first conductive layer and the flatness of the side, away from the substrate, of the first planarization layer are improved. According to the technical scheme provided by the embodiment of the invention, the planarization effect can be improved, the thickness of the planarization layer is reduced, and the planarization effect does not depend on the thickness of the planarization layer.