Low-density polyethylene (LDPE) metal oxide nanocomposites are used as high-voltage insulation in AC cables to reduce space charging and other issues. Nanoparticles such as SiO2, MgO, and ZnO are used as fillers in polyethylene matrix to achieve good electrical, thermal, and mechanical properties such as space charge reduction, increased surface and volume resistance, and high dielectric stress bearing capabilities. LDPE/Al2O3 compounds are prepared at concentrations of 1%, 3%, 5%, and 7% for nanofillers and at concentrations of 10%, 20%, 30%, and 40% for micro fillers. The dielectric strength of the LDPE/Al2O3 sample was measured at different temperatures to determine the effect of temperature on the dielectric strength value. To check the various properties of the samples, the tensile strength test has been applied. The Whale Optimization Algorithm (WOA) was used to calculate the optimal Al2O3 filler percentage for the best dielectric strength value.