Thermoplastic polypropylene (PP)-based cable insulation materials, as a new generation of environmentally friendly cable insulation materials, have the potential to replace traditional XLPE. Due to the high crystallinity of PP materials, the material itself is relatively brittle, making it prone to stress whitening when subjected to external forces. This paper focuses on the study of the stress whitening phenomenon in a commercially modified PP material, examining its effects on the crystal structure and electrical properties. Through relevant tests and analysis, it was found that after stress whitening, the resistivity of PP-based materials decreases, the dielectric loss factor increases, and the breakdown field strength decreases. The crystal structure shows a certain degree of damage after stress whitening, with impact-induced stress whitening causing more severe crystal damage than bending-induced stress whitening. After annealing treatment at 80 ℃ for 7 days, the crystal structure and electrical properties exhibit a certain degree of recovery, with better recovery observed in samples subjected to bending-induced stress whitening.