Graphene modified with polydopamine (PDA) which displays promoted dispersibility in organic solvent was prepared through self-polymerization of dopamine onto graphene oxide (GO) and subsequent chemical reduction of GO. The PDA coated reduced GO (RDGO) is then homogeneously introduced into poly(vinylidene fluoride) (PVDF) matrix. Fourier transforminfrared spectroscopy (FTIR) proves hydrogen bonding interaction between RDGO and matrix owing to the PDA layer. The as-prepared PVDF/RDGO composites exhibit drastic change of electrical conductivity near percolation threshold which occursat quite a low level of filler loading (0.643 wt%) due to the semiconducting PDA layer and good dispersion of graphene. The dielectric properties of composites undergo abrupt increase in the vicinity of percolation threshold. Specifically, the dielectric constant of PVDF with 0.7 wt% RDGO increases to 176, about 17 times of neat PVDF, while the loss tangent is as low as 0.337. The enhancement of dielectric constant probably rises from duplex interfacial polarization induced by graphene-semiconductor interface and semiconductor-insulator interface. Meanwhile, the semiconducting PDA layer successfully suppresses the loss tangent near percolation threshold. The composites displays advantages in excellent dielectric properties and good flexibility and processibility guaranteed by low loading of RDGO, which is suitable for the development of dielectric materials for energy storage.