The thermal conductive model of inorganic particulate-filled polymer composites was proposed based on the ANSYS parametric finite element technology, and the numerical simulation of the effective thermal conductivity of low-density polyethylene (LDPE) composite filled with graphite powder was made. It was found that the simulated effective thermal conductivity of the composite increased nonlinearly with an increase of the filler volume fraction, and increased with increasing the particle diameter. Finally, the finite element numerical simulations were compared with the experimental measured data from the LDPE/graphite composite under the same conditions reported in the literature. The results showed that the simulations of the effective thermal conductivity were roughly close to the experimental measured data.