In　this　paper,　quaternary　ammonium　salt　type　Gemini　surfactant　G12　was　designed　and　synthesized,　and　its　structure　was　characterized　by　infrared　and　nuclear　magnetic　resonance.　The　surface　tension,　permeability,　emulsification　ability　and　cleaning　of　insulator　surface　contamination　in　the　composite　system　were　tested,　and　the　test　results　showed　that　it　had　low　critical　micelle　concentration　(cmc)　and　good　emulsification　performance.　Due　to　the　presence　of　rigid　groups,　the　permeability　is　average.　When　quaternary　ammonium　Gemini　surfactant　G12　is　mixed　with　permeant　JFC-E,　and　is　combined　with　auxiliary　and　organic　solvent,　the　cleaning　rate　of　insulators　can　reach　more　than　90%.　©　2023　EDP　Sciences.　All　rights　reserved.