Abstract: The phase behavior diagram has been drawn and analysed in DTAB－SL mixed system and the influences of temperature and inorganic salt upon “aqueous surfactant twophase(ASTP)” have been studied systematically. The results show that ASTP region when cationics is in excess(ASTPC) is larger and stabler than that when anionics is in excess (ASTPA)(to see Fig.1). The higher the temperature and the inorganic salt concentration(NaBr), the less ratio of upper to lower volume( Vup/Vlow) in ASTP system(to see Table 1～2). Vesicles generally existed in upper and lower phases of ASTP.

Key words: Aqueous surfactant twophase(ASTP), Vesicle, Ratio of upper to lower volume, Temperature, Inorganic salt