<p>The excellent electrical properties of polypropylene (PP) make it a widely used material for power cable insulation. However, its vulnerability to the potential impact of water molecules and aggressive ions in complex environments should be taken into consideration. The microscopic interaction mechanism between H₂O, Cl⁻, NO₃⁻, and SO₄²⁻ and polypropylene power cable is investigated in this study using a combination of density functional theory and molecular dynamics methods. The analysis of between molecules and hybrid systems of PP provides insights into the influence mechanism of active sites, interaction energy, and cohesive energy density on the reaction. The results reveal that the H-U site of PP exhibits a higher propensity for interaction with water molecules and aggressive ions in the intermolecular, with the largest interaction energy observed between SO₄²⁻ and PP. In the hybrid system, not only does SO₄²⁻ exhibit the highest interaction energy, but it also displays superior cohesive energy density and exerts stronger erosion on PP materials. This study elucidates the microscopic interaction mechanism between water molecules and aggressive ions with polypropylene power cable in complex operating environments from the microscopic level, providing a specific theoretical foundation for modifying the erosion resistance of PP materials.</p> Graphical Abstract <p></p>