To optimize the components of cross-linked polyethylene (XLPE) insulation material for high voltage cable, gel extraction, thermal elongation, torque rheometer and weight loss method were applied to investigate the crosslinking characteristics of materials, the thermal aging characteristics of XLPE were characterized by infrared spectroscopy, and the mechanical and electrical properties of XLPE were tested. The results show that the gel content and crosslinking degree of XLPE increase, the mechanical properties slightly change and the temperature sensitivity of AC breakdown strength significantly reduces as the content of crosslinking agent (DCP) increases. The content of DCP is determined to be 1.8 phr with priority given to crosslinking characteristics. With the increase of antioxidant content, the crosslinking degree of XLPE insulation decreases and the thermal elongation increases slightly. Compared with XLPE using 0.3 phr antioxidant 300 alone, the combination of 0.15 phr antioxidant 1010 and 0.15 phr antioxidant 1035 realizes a synergistic effect to more significantly inhibit the formation of carbonyl group and thermal-oxidative aging process. Besides, they improve the scorch resistance of XLPE without reducing the crosslinking degree, thus avoiding the influence of pre-crosslinking on the performance of XLPE insulation. Moreover, the improved XLPE insulation material has the less temperature sensibility in breakdown and lower dielectric loss.