Selective localization of carbon black (CB) at the interface of polymer blends was achieved by the method that EBA-g-MAH was first reacted with CB, and then blended with poly(ethylene-co-butyl acrylate)/nylon6 (EBA/PA6). In CB-filled EBA/PA6 blends, EBA and PA6 phases formed cocontinuous morphology and CB was localized in PA6 phase. The percolation threshold was 5 wt%. A single PTC (positive temperature coefficient) effect was observed in this composite. The appearance of PTC effect was originated from the thermal expansion of EBA phase. In the EBA-g-MAH filled EBA/PA6 blends, TEM results showed that CB particles were induced by EBA-g-MAH to localize at the interface, resulting that the percolation threshold was much lower than that of EBA/PA6/CB. Influence of morphology on PTC effect of EBA/PA6/EBA-g-MAH/CB composites was studied. In the composites with sea-island morphology, the conductive network was fabricated by dispersed phase and CB at the interface. Thermal expansion of matrix interrupted the contact of dispersed phases and conductive network formed by CB particles at the interface, resulting in the double PTC effect. The composites with co-continuous morphology exhibited single PTC effect due to the fact that conductive network was only fabricated by CB localized at the interface. POLYM. ENG. SCI., 53:2640–2649, 2013. © 2013 Society of Plastics Engineers