Abstract: Cross-linked polyethylene (XLPE) has been widely used for the cable insulation of high-voltage cables due to the excellent electrical insulation properties. However, the cable insulation will suffer from different degrees of aging after long-term service, which reduces the insulation performance and leads to power supply failure. To evaluate the insulation aging status of XLPE with different operating years, various measurements including trap parameters, space charge, surface chemical composition, thermal properties and dielectric properties were performed and analyzed. The results show that the surface potential decay rate and trap charge density of the XLPE cable increase gradually with the increasing operating years. Meanwhile, the charges of heteropolarity accumulate in new cables and are dominated by deep traps, and the charges of homopolarity accumulate in cables that have been run and are mainly dominated by shallow traps. The results of melting-crystallization performance from DSC show the crystallinity of XLPE cable decreases with the increase of operating years, which makes it easier for carriers to form a breakdown channel in the sample. Further, shallow traps have a weak charge trapping capability, resulting in a lower breakdown field strength of the material. The change of cross-linking byproducts and the formation of carbonyl groups increase the density of shallow traps in the insulation during cable aging or failure. In a word, with the increase of operating life, the XLPE insulation deteriorates obviously, generating C＝C, C＝O, —OH as well as other polar groups and physical defects to form new traps, increasing the density of shallow traps in the meterial, reducing the breakdown performance of the cable insulation.