Abstract: Magnesia-alumina spinel additives for FCC process,were prepared by sol-gel method.Test were carried out in a fix bed reactor to observe the effect of olefin reduction in FCC gasoline,and the influence of preparation temperature and Mg/Al amount-of-substance ratio were studied as well.Results indicated that the additives prepared at 80 ℃ and having a Mg/Al amount-of-substance ratio of 1.0 showed the best reaction activity,the olefin-reducing rate was over 20% in FCC gasoline.The reaction mechanism was also studied.XRD results showed that MgAl<SUB>2</SUB>O<SUB>4</SUB>&#8226;MgO spinel could improve hydrogen migration reaction activity.<BR>