Disclosed are a nanostructure array substrate, a method for fabricating the same, and a dye-sensitized solar cell by using the same. The nanostructure array substrate includes a plurality of metal oxide nanostructures vertically aligned on the substrate while being separated from each other. The metal oxide nanostructures include nanorods having a ZnO core/TiO2 shell structure or TiO2 nanotubes. The method includes the steps of forming ZnO nanorods vertically aligned from a seed layer formed on a substrate; and coating a TiO2 sol on the ZnO nanorods and sintering the ZnO nanorods to form nanorods having a ZnO core/TiO2 shell structure. The transparency and flexibility of the substrate are ensured. The photoelectric conversion efficiency of the solar cell is improved if the nanostructure array substrate is employed in the photo electrode of the dye-sensitized solar cell.