Abstract: In order to reduce the destruction impact of vanadium oxide on cracking component in FCC catalyst, the composite oxides containing vanadium, rare earth or alkaline earth metal were prepared respectively. The structures of composites were characterized by XRD, DTA, TPR and temperature-programmed surface reaction（TPSR-MS）. The mechanism of thiophenic sulfur removal was studied. The results indicate that lanthanum, cerium or Mg can react with vanadium to form a high melting point complex oxide: LaVO4, CeVO4 and MgV2O6, respectively. It is found by TPR that LaVO4 and CeVO4 can increase the reduction temperature of vanadium oxide, indicating the activity decline of the lattice oxygen. The results of TPSR-MS demonstrate that the main reaction for thiophene and cyclohexane on complex oxides (CeVO4 and LaVO4) is oxidation and dehydrogenation, respectively. TPSR-MS results show that the addition of magnesium in rare earth vanadates can significantly increase the conversion rate of thiophene. The heavy oil MAT results show that the catalyst containing 10% La-Mg-V can reduce the sulfur in naphtha by 67.2%.