The　interaction　of　Gemini　surfactant　C12-s-C　12·2Br　with　aqueous　suspension　of　fumed　silica　have　been　investigated　by　DLS,　Zeta　potential,　conductivity,　pH　value　and　fluorescence.　With　the　increase　of　surfactant　concentration,　four　regions　exist　during　the　adsorption　and　aggregation　process,　which　can　be　recognized　as　ion　exchange　adsorption,　electrostatic　repulsion,　adsorption　layer　formation　by　hydrophobic　interactions　and　free　micelle　formation.　The　Gemini　surfactant　C　12-s-C12·2Br　shows　strong　adsorption　ability　on　the　fumed　silica.　Zeta　potential　was　turned　from　negative　to　positive　by　the　addition　of　small　quantitates　of　C12-s-C12·2Br.　The　＂dispersion-flocculation-dispersion＂　phenomena　was　observed　for　the　addition　of　s=2　during　0.1　to　4　mmol·L-1.　5%　fumed　silica　dispersion　system　can　be　gelled　by　s=2　of　1mmol·L-1.　These　phenomena　have　never　been　observed　for　the　systems　containing　s=4　and　s=6.　©　2011　Published　by　Elsevier　B.V.　Selection　and/or　peer-review　under　responsibility　of　International　Materials　Science　Society.