An improved analytical model is developed based on the average interparticle distance (IPD) concept to predict the percolation threshold of conducting polymer composites containing disc-shaped nanoparticles with high aspect ratios. Two different conditions were taken into account in the model in terms of particle distribution, namely two- and three-dimensional random orientations. A 10 nm interparticle distance is adopted as the electrical conducting criterion according to the tunneling mechanism, and the percolation threshold is estimated as a function of geometric shape of the nanoparticle. A parametric study suggests that the thickness and diameter of fillers are important factors that determine the percolation threshold of conducting nanocomposites. The accuracy and the applicability of the present IPD model are verified by comparing with several existing models and experimental data for graphite nanoplatelet reinforced polymer nanocomposites. It is shown that the current model presents much better agreement with experimental results than existing models.