Multilayer PVDF-BaTiO3/PDDA ultrathin composite film was prepared in the presence of BaTiO3 nanoparticles by electrostatic self-assembly method, and quartz crystal microbalance was in situ used to monitor the whole film fabrication process. The results showed that the film with 1: 1 weight ratio of PVDF to BaTiO3 is more uniform than that of 2: 1 ratio. The monolayer film thickness ranges from 19 to 25nm calculated by Sauerbery equation. Coupling agent enhanced the dispersion capability of BaTiO3 nanoparticles, and the ferroelectric property of PVDF/PDDA composite ultrathin film was improved with the assistance of inorganic nanoparticles.