Abstract: The interior electric field of a two-phased composite material was simulated by using Monte Carlo and finite
element methods with 3-dimensional model, from which the macro dielectric constant, ε_m, of the material was calculated. The results show
that the percentage of electric field energy stored in the low-permittivity phase to total energy calculated with 3-dimensional model is larger than that
calculated with 2-dimensional model. Since the 3-dimensional model accords with the fact that the particles in real composite material are more
parallel than serial connected, the simulated distribution of the electric field and ε_m with 3-dimensional model are more accurate than with 2-dimensional
model. A new equation for predicting the macro dielectric constant of a two-phased compound derivedis: ε^α_m=V₁ε^α₁+V₂ε^α₂, where α=(V²₁+20V₁V₂+20V₁V₂+5V²₂)/11, V₁+V₂=1 and ε₁<ε₂. This equation agrees
well with the data from some literatures.

Key words: composite material, monte carlo method, finite element method, mixing rule