Three　bisimidazole　ring　ionic　liquid　precursors　M1,　M2and　M3containing　methyl,　ethyl　and　butyl　substituents　were　synthesized　and　characterized　by　1H　NMR,　13C　NMR,　ES1-MS　and　TG/DTG/DSC.　A　series　of　bisimidazole　ring　ionic　liquid　catalysts　A1Cl3/M1,　A1C13/M2and　A1C13/M3were　synthesized　based　on　the　corresponding　precursors　M1,　M2and　M3,　and　their　acidity　was　studied　using　UV-visible　and　acetonitrile　IR　(CAN-IR)　characterization　methods.　Furthermore,　the　effect　of　substituents　on　the　isomerization　performance　of　n-hcxane　was　studied,　and　its　reaction　process　conditions　were　also　optimized.　The　results　shows　that　the　catalyst　A1C13/M2synthesized　by　bisimidazole　ring　ionic　liquid　with　ethyl　as　the　substituent　has　more　Bronsted　and　Lewis　acid　sites,　which　is　helpful　for　the　isomerization　reaction.　Under　the　optimal　process　conditions:　molar　ratio　of　A1C13to　Cl-(2.　1　:　1)　in　the　precursor　M2,　reaction　temperature　of　30　°C,　reaction　time　of　10　h　and　mass　ratio　of　catalyst　to　oil　(1　:　1),　the　n-hexane　conversion　rate　is　74.　52%,　and　the　selectivity　and　yield　of　isohexane　are　29.　51%　and　21.　99%,　respectively.　©　2022　Science　Press.　All　rights　reserved.