The dispersive and conductive properties of polymer nanocomposites are investigated simultaneously using the molecular dynamics simulation method. Four factors influencing the dispersion and conductivity are concerned, including polymer-nanoparticle interaction, nanoparticles with grafted chains, cross-linking of polymer chains, and blending of polymer. It is shown that the variation of the conductive probability is not linearly related to the corresponding dispersion for all the four concerned cases. As the interaction strength increases, the dispersion of the nanoparticles appears to first increase and then drop, while the conductive probability increases monotonously. Increase of the grafting density on nanoparticles can bring about the modification of the dispersion, whereas the variation of the conductive probability is M-type. The dispersion effect increases monotonously with the increasing cress-linking density, but the corresponding conductive probability appears to first increase and then drop. The dispersive effect of nanoparticles monotonously decreases as the ratio of added incompatible polymer increases; however, the corresponding conductive probability has the maximum value.