A Mg-rich Mg-Al spinel modified with CuO and CeO2 via a cogelling method was used to remove SO2 from fluid catalytic tracking (FCC) flue gas. It was found that the generation of a MgO-CuO solid solution was prevented in the presence of CeO2. So CuO had a better dispersion on the adsorbent surface and showed a better catalytic oxidation activity. At the same time, when CuO was added, oxygen defects were found increased greatly in the lattice of CeO2 by Raman spectra and in situ FTIR spectra analyses. This improved the oxygen adsorption capacity of the catalyst. High catalytic oxidation activity and oxygen adsorption capacity of the catalyst enormously promote oxidation of SO2 to SO3, which is much easier to adsorbed by spinel. The SO2 breakthrough time was doubled when the Mg-Al spinel was modified with both CuO and CeO2.