To further improve the chemical aging resistance of Electrical Insulation Materials (EIM) for railway passenger trains, this paper prepares a modified polyvinyl chloride (PVC) with the UV Absorber (UVA) by the copper catalyzed azide-alkyne addition reaction. By analyzing the H-NMR (Nuclear Magnetic Resonance) and infrared spectrums, it is proved that UVA-modified PVC has been prepared successfully. In the end, based on the curve of the infrared spectroscopy as a function of carbonyl group content, the UV aging resistances of modified and common PVCs are compared. The findings show that the common PVC will turn into yellow after long-term ultraviolet irradiation, and the carbonyl in the compound rapidly increases, developing into severe aging; the insulationand physical structure properties has significantly deteriorated; while the modified PVC basically remains unchangedin color after 200h UV irradiation, and the carbonyl content increases at a rate much lower than the common PVC. Given the above, it is thus clear that the UVA-modified PVC prepared presents a better UV aging resistance.