Abstract: In order to develop inorganic/organic dielectric composites with high energy storage density, the finite element method was adopt to study the effects of both morphologies and dielectric constant of fillers on the dielectric properties of inorganic/organic composites, including the ratio of dielectric constant of spherical filler to matrix (k), the size (100-300 nm) and the arrangement of spherical fillers, the aspect ratio of fiber fillers (α) and the sphericity of nanoplate fillers (β). The results show that the dielectric constant of composites doesn't change significantly when k exceeds 20. The composites will get large dielectric constant when the spherical fillers are chained along the direction of the electric field. Large electric displacement and large electric field appear at the interface between the spherical fillers and matrix, indicating that this arrangement is beneficial to the improvement of the dielectric constant of the composites, but weakens the breakdown resistance. When the spherical fillers are randomly distributed in the matrix, the sizes of fillers have little effect on the dielectric constant of composites. Fiber fillers with large α and the long axis along the direction of electric field will result in large electric displacement, which indicates this filler will improve dielectric constant of composites. The nanoplate fillers with small β bring out lower electric field at the interface, indicating that the composites possess higher breakdown resistance.