The novel ionic liquids with an alkane sulfonic acid group were prepared and used for removal of trace olefins from aromatics (referred to as oil). The structures and acidities of the ionic liquids were experimentally characterized and systematically analyzed. The influences of various reaction parameters, such as the stirring speed, viscosities of the ionic liquids, molar fraction of ZnCl2, dosage and type of ionic liquid, reaction temperature, reaction time, and the reusability of the ionic liquid, were investigated. It was found that the ionic liquid 1-(3-sulfopropyl)-3-methylimidazolium bromochlorozincinate ([C(3)SO(3)Hmim]Br-ZnCl2) with the molar fraction of ZnCl2 of 0.67 exhibited a better performance for olefin removal. Meanwhile, the experimental results showed that after the reaction had taken place at 373 K for 1 h, olefin conversion of 29.54% was obtained with the mass ratio of IL to oil of 0.2. Even though the reusability of the ionic liquid was not good, the separation of the reaction mixture can be performed by simple decantation.