A quaternary nanocomposite polycarbonate (PC)-multi-walled carbon nanotubes (MWCNT)/SEBS-g-MA (SM)-AlN is prepared by controlling the selective distribution of nano-fillers via meltblending. Through a two-step mixing method, surface modified AlN is selectively dispersed in the island-like SM phase; meanwhile, MWCNT acting as bridges are mainly located in the continuous phase of PC. This 'island-bridge' morphology is confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The selective localization results agree well with the theoretical predictions. Dynamic mechanical analysis (DMA) indicates that the addition of hybrid fillers improved the storage modulus selectively. Thermogravimetric analysis (TGA) shows that the thermal stability of the PC/SM blends increased significantly; the degradation kinetic has also been changed due to the synergistic effects of the fillers. This novel ` island-bridge' network contributes a higher thermal conductivity at low filler content as the effective thermal conductivity reached 0.72 W m(-1) K-1, which is three times higher than that of 70PC/30SM. The experimental observations coincide well with the optimizing model results.