Abstract: The alkylation of olefins with thiophenic sulfur containing compounds in FCC gasoline using HY zeolite catalyst was studied. The effect of reaction temperature and reaction time on the alkylation reactions, the changing of sulfur existing forms and hydrocarbon compositions prior and post to reactions was investigated. Test results showed that with HY zeolite catalyst, under a reaction temperature of 130℃ and a reaction time of 60 min, about 90.98% of the sulfur containing compounds in the light fraction (＜120 ℃) were transferred to the heavy fraction (＞120 ℃). Combined process of this alkylation technique with hydrofining process was compared with the selective hydrodesulfurization (RSDS) process, it was found that this combined process could release the load of heavy fraction hydrofining due to higher cut point, the sulfur content of light fraction reduced and the octane loss of gasoline was less.