Abstract: A novel ionic liquid (IL), composite IL, which contained enough quantity of multi-center ligand, AlCl4CuCl－, was successfully synthesized. The effects of reaction temperature, reaction time, stirring speed and isoparaffin/olefine (I/O) ratio on the composite-IL-catalyzed alkylation were studied. The results showed that the research octane number (RON) of the yielded alkylate gasoline can be higher than 100 under the optimal conditions: stirring speed > 1500r/min, reaction temperature < 20℃, I/O ratio >15 and reaction time in range of 5min to 10min. The multi-center ligand, AlCl4CuCl－, should be accounted for the super selectivity of trimethylpentane (TMP) of isobutane alkylation catalyzed by composite IL.