Calculation of the dielectric permittivity of composite materials are becoming important to design new materials such as polymer/ceramic composite capacitors for 3D embedding in PCB. In this study, we have developed new software, multi-scale finite element method, where the microstructure of a composite is modeled by an assemblage of some unit structures and FEM calculation is done for each unit followed by calculation for the assemblage of the units. The dielectric permittivity and loss tangent of polymer/BaTi03 composites were calculated. It was found the permittivity of completely dispersed composites was above 200 at 60 vol% of BaTiO3 particles.