This study for the first time investigated the structure of a supported oxide system by SEELFS, the research of which had significance not only in the preparation of advanced solid base catalyst but also in the application of SEELFS technique onto a supported system. We present here the experimental results of a supported oxide system by SEELFS through the structural analysis of magnesia on a gamma-alumina carrier. Using a fitting procedure based on an EXAFS-like formula and the phase shifts of a model compound of MgO, the coordination distances for Mg-O and Mg-Mg shells were obtained serniquantitatively and the coordination numbers obtained qualitatively. In addition, the contribution terms in the SEELFS oscillation of Mg K-edge of magnesia were also analyzed by the back Fourier transform of a corresponding Fourier function.