The X-ray diffraction (XRD) -phi scan measurement of an Y1Ba2Cu3O7-delta/CeO2/MgO/SrTiO3 multilayer revealed noticeable changes in the effect of the MgO seed layer on the crystalline orientation of the YBCO/CeO2 overlayer as the thickness of the MgO layer increased from 20 to 60 angstrom. Such a phenomenon was confirmed to originate from the thickness-dependent characteristics of the MgO seed layer itself. Another interesting property of the MgO seed layer, which was deposited by e-beam evaporation, is that the CeO2 overlayer did not grow epitaxially on it unless its surface was heat treated in an oxygen atmosphere.