With　p-N,N-dimethylaminobenzonitrile　(DMABN)　as　a　probe,　the　variations　of　the　intensity　of　its　second　fluorescence　emission　(I-a)　and　the　corresponding　characteristic　wavelength　(lambda(a))　with　the　surfactant　concentration　(c),　here　the　examined　surfactants　(C(12)TABr,　SDS,　C12E23,　and　C-12-3-C-12　center　dot　2Br),　were　measured　by　Hitachi　F4500　fluorescence　spectrophotometer.　The　results　showed　that　both　the　break　point　on　the　I-a-c　curve　and　the　minimum　of　the　derivative　variation　corresponding　to　the　lambda(a)-c　curve　agreed　very　well　with　the　critical　micelle　concentration　(cmc)　of　the　surfactant　in　aqueous　solution　as　measured　by　surface　tension　technique.　Due　to　strong　aggregation　of　C-12-3-C-12　center　dot　2Br　in　aqueous　solution,　the　information　about　loose　micellar　structure　could　be　obtained　by　its　lambda(a)-c　curve.