Mixed　micellization　of　quaternary　ammonium　dimeric　surfactants,　C-12-s-C-12　.　2Br(　s　=2,　3,　4,　6),　and　a　nonionic　surfactant　C12E10　or　C12E23　in　aqueous　solution　have　been　investigated　using　conductivity　measurement.　The　results　show　that　C-12-s-C-12　.　2Br　and　C12E10　or　C12E23　form　mixed　micelles.　The　values　of　the　total　critical　micelle　concentration　lie　always　among　cmc　and　cmc,　which　are　the　critical　micelle　concentrations　for　individual　surfactant　1　and　surfactant　2,　respectively.　Addition　of　a　few　nonionic　surfactant,　for　example　alpha(2)　=　0.1,　the　molar　fraction　of　C12E10　or　C12E23　in　the　mixed　micelle　exceeds　0.　35.　With　further　increasing　the　concentration　of　the　nonionic　surfactant　in　solution,　the　main　component　in　the　mixed　micelles　becomes　gradually　C12E10　or　C12E23.