This study aims to develop large-scale commercial Cross-Linked Polyethylene (XLPE) nanocomposites used for industrial applications with power cables insulations. To achieve this goal, XLPE/zinc oxide nanocomposites were prepared with four unique loadings of Zinc Oxid (ZnO) nanoparticles: 0.5, 2, 3.5 and 5 wt.%, in the presence of appropriate coupling agent which used to reduce the agglomeration of nanoparticles and to improve the compatibility inside the polymer matrix. Amino silane was the coupling agent used in this study and the nanocomposites preparation was done using the melt blending method. The morphology and the distribution of nanoparticles inside XLPE polymer were studied using Field Emission Scanning Electron Microscopy (FE-SEM). The mechanical properties were also evaluated. Using Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA), the thermal properties for nanocomposites were investigated. The dielectric properties of these prepared XLPE/ZnO nanocomposites were studied by measuring the loss tangent (tan δ) and the dielectric constant (ɛr) under frequencies ranging from 1 Hz to 1 MHz. The AC Breakdown Voltage (AC-BDV) was also measured using a controlled high voltage testing transformer (50 Hz) under the sphere-to-sphere field then; the AC dielectric strength was calculated using the Finite Element Method (FEM) technique.