N,N-dimethylferrocenylmethylhexadecylammonium bromide (FC16AB) was synthesized and characterized by the spectra of UV-Visible, FTIR 1H NMR, ESMS, etc. Surface tensions of different concentrations of FC16AB water solution were measured, which shows that FC16AB has good surface activity. The surface pressure-area (pi-A) curves and differentiated pi-A curves of FC16AB on water, Cl-, and SO(4)2- subphases were studied. The results indicate that FC16AB molecules can form the most stable monolayer on the subphase containing Cl-.