PbTiO3 ultrafine particle-stearic acid composite ultrafine film was fabricated by LB film technology,and characterized by π-A curve and atom force mircoscope. The UV-visible absorption,fluorescent and Raman spectra showed that: PbTiO3 ultrafine particle and composite LB film had quantum-size effect and dielectric confinement effect. In composite ultrathin film, PbTiO3 ultrafine particles had photo-luminescence at room temperature and their soft-mode changed.