A three-phase approach based on electrostatic interaction was proposed to achieve the film formation by assembling passivated nanoparticles at air-water interface. The cationic surfactant with suitable polarity can serve as feedstock molecules to bond with aqueous Ag nanoparticles at water-chloroform interface. Because of the decrease of solubility in water, Ag nanoparticles would gradually disengage from bulk solution and organize on water surface.