In this paper, NBCTO/epoxy composite films with different contents of NBCTO were prepared by solution mixing and casting method. The structure, morphology, thermostability and dielectric properties of the composite films were studied by X-ray diffraction, scanning electron microscopy, thermo-gravimetric analysis and broadband dielectric spectrometer. The composite film showed a homogeneous structure and better thermostability, and the dielectric permittivity was almost independent of the frequency range from 10 to 10 6 Hz at room temperature. The dielectric permittivity and dielectric loss of NBCTO/epoxy composite film increased with increasing in NBCTO content, and the dielectric permittivity was as high as 37.10 whereas the dielectric loss was only 0.019 at 1 kHz when the NBCTO volume fraction reached 50 vol%. Theoretical analysis indicated that the dielectric permittivity calculated by the EMT model was close to the experimental data. The results showed that NBCTO/epoxy composite might have potential applications in the electronic devices.