Abstract: In response to the problem of oxidation discoloration of copper conductors in XLPE insulated cables during the chemical crosslinking process, this study revealed the main cause of oxidation through mechanism analysis: In addition to the high-temperature environment, the catalytic oxidation triggered by the migration of peroxide crosslinking byproducts (phenolic, aldehyde, and ketone small molecules) towards the conductors is the core inducement. An innovative “conductor-insulation collaborative protection” system is proposed: On the conductor side, high-temperature resistant benzotriazole (BTA) passivation (0.3% concentration) is applied and semi-conductive nylon tape is wrapped; On the insulation shielding side, the material formulation is optimized (adding an anti-aging agent MB/DNP compounding system); At the process end, nitrogen segmented protection and precise control of crosslinking parameters are implemented. Industrial verification shows that this solution reduces the oxidation rate of conductors by 92%, providing a dual theoretical-technical solution for industry pain points.