In order to prepare new functional macromolecule material, the coupling reaction of acenaphthene catalyzed by [Bmim]Cl/FeCl3 ionic liquid was investigated under mild reaction conditions and without any additional organic solvent. Pure 3,3’-biacenaphthene, which is used as intermediate of function aromatic polymer material, was obtained by recrystalling and column chromatography from the reaction mixture and was determined by GC/MS, 1HNMR and FTIR analysis. The influence of various reaction conditions on the coupling reaction of acenaphthene were studied by GC analysis and the optimum synthesis conditions of the reaction were obtain. Under optimun conditions, the yield of 3,3’-biacenaphthene will be 63.5 % and selectivity of that will be 85.6 %. Further more, [Bmim]Cl/FeCl3 is environmentally benign catalyst and solvent and can be reused.