Abstract: FT-IR spectra of different kinds of sulfides adsorbed on CeY zeolite were collected. Based on that, the effect of olefins (with 1-octene, 1,5-hexadiene, and cyclohexene as model compounds) in FCC gasoline on the desulfurization performance of CeY were investigated. The results revealed that a ring-opening catalytic reaction occurs after the sulfides are adsorbed. As compared with alkyl thiophenes, benzo thiophenes are more stable. The strong interactions between the double bond in alkenes with the Ce cation in CeY lead to the formation of π-complexes through the σ—π electron donations, which competes with the SM function between thiophene and CeY. The amounts of polymers formed on the CeY surface increases with the concentration of alkenes, which may occupy the active sites and clog the pores in CeY; this will reduce the adsorptive selectivity for removing thiophene from the model fuel.