BaTiO3 nanofibers with a large aspect ratio prepared via electrospinning and modified by dopamine were used as dielectric fillers in poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)-based nanocomposites. Highly flexible polymer nanocomposite films were fabricated via a simple solution-cast method. Enhanced dielectric permittivities were obtained at a low volume fraction of BaTiO3 nanofibers. The breakdown strength of the polymer nanocomposites was also improved, which is favorable for enhanced ferroelectric properties in the nanocomposites. P-r similar to 9.1 mu C cm(-2) was achieved in the nanocomposites with 10.8 vol% BaTiO3 nanofibers. The improved breakdown strength and enhanced ferroelectric properties are attributed to the combined effect of the surface modification by dopamine, the large aspect ratio of the BaTiO3 nanofibers and the improved crystallinity of the polymer nanocomposites induced by the BaTiO3 nanofibers.