Sodiumbenzenesulfonate　(SNzS)　and　sodiumnaphthalenesulfonate　(SNphS)　added　in　the　solution　strongly　associated　with　quaternary　ammonium　gemini　surfactants　(C12-s-C12·2Br),　which　increased　the　hydrophobicity　of　C12-s-　C12·2Br　molecule　and　obviously　enhanced　their　adsorption　at　the　air/water　interface　and　aggregation　in　the　solution.　This　resulted　in　great　increase　in　the　efficiency　and　the　effectiveness　in　surface　tension　reduction,　and　the　formation　of　small　aggregates　in　the　solution　at　very　low　concentration　of　surfactant.　Thus,　the　cmc　obtained　by　surface　tension　method　was　only　of　apparent　significance　and　it　reflected　the　critical　concentration　when　the　surfactant　reaching　saturated　adsorption　at　the　air/water　interface.　Compared　with　SNzS,　SNphS　promoted　more　effectively　both　adsorption　and　aggregation　of　C12-s-C12·2Br　due　to　its　higher　hydrophobicity.　©　Editorial　office　of　Acta　Physico-Chimica　Sinica.