Three-phase nanocomposite films, made up of polystyrene (PS), bismuth ferrite (BiFeO3; BFO) and conducting particles of graphite nanopowder (GNP), were prepared by solution casting techniques. Using different volume fractions of GNP, the dielectric properties of the nanocomposites were analyzed by impedance analyzer with various ranges of electric fields. To support our discussions, percolation theory was used to know the dielectric behavior of the PS-BFO-GNP nanocomposites and the percolation threshold was observed at 3 vol% of GNP. The dielectric constant of PS-BFO-GNP nanocomposites reached as high as similar to 75 at 0.1 kHz, which was much higher than that of pure PS, PS-BFO and PS-GNP nanocomposites. Furthermore, the P-E hysteresis loop study was carried out to observe the ferroelectric behavior of the nanocomposites.