A series of linear low-density polyethylene (LLDPE)-natural rubber (NR) blends of composition 80/10, 70/20, 60/30, 50/40 and 40/50 containing nano-sized fillers montmorillonite (MMT) and Titanium(IV) Oxide (TiO2) were produced by a twin-screw extruder with maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MAH) of 10 wt% as a compatibilizer. An electrical performance test through partial discharge (PD) characteristics using CIGRE Method II test was conducted to study the electrical performance of the samples. Morphological analysis using scanning electron microscope (SEM) and Energy Disperse X-ray spectroscopy (EDX) also conducted after the samples of composite were subjected to high voltage stress. The degradation of composite surfaces were analyzed. Then tensile test carried out to investigate the mechanical performance of the composites. The combine results of PD characteristics and tensile properties described the insulating performance of the composites. The results revealed that total PD numbers decrease with increasing of weight percentages of natural rubber in the composition of the composite without any filler.