To explore the role of matching water affinities between the oppositely charged headgroups, the micellization of cetyltrimethylammonium bromide (CTA(+)Br(-))/sodium dodecanoate (Na+L-) mixed system and the CTA(+)Br(-)/sodium dodecylsulfonate (Na(+)AS(-)) mixed system has been investigated by the surface tension method and molecular dynamic (MD) simulation. In comparison with the CTA(+)Br(-)/Na+L- system, the CTA(+)Br(-)/Na(+)AS(-) system shows stronger micelle formation ability, smaller critical micelle concentration (cmc), and stronger synergistic effect arising from the higher degree of matching water affinities between CTA(+) and AS(-). To explore the role of matching water affinities between the oppositely charged constituent counterions, the micellization of CTA(+)X(-)/Y+L- mixed systems with various counterions has been investigated. The higher degree of matching water affinities between counterions X- and Y+ and the higher degree of mismatching water affinities between headgroups and counterions are unfavorable to the screening effect of counterions on the electrostatic attraction between headgroups CTA(+) and L-, leading to stronger micelle formation ability and smaller cmc and vice versa. MD simulation results also indicate that, for the mixed micellization of cationic/anionic surfactants, the role of matching water affinities between oppositely charged headgroups is more important than that between oppositely charged constituent counterions.