In order to investigate the reliability of the continuous operation of the high voltage cross-linked cable which reaches the design life limitation,a 180-day pre-qualification test method is carried out on a section of high-voltage cross-linked cable which has been in operation for 32 years. By comprehensively analyzing and comparing the differences of electric field strength and temperature field in the inner,middle and outer layers of cable insulation during the test,the testing conditions of each insulation layer are converted into the surface of conductor core,and the corresponding equivalent testing conditions are obtained. It is found that equivalent testing conditions of the medium and outer positions are close to the cable practical operation condition. Several diagnostic measurements are conducted to analyze the micro-structure and aggregation structure among the samples. The results show that the inner layer produces more small molecular chains and oxygen-containing groups in the high-strength test condition. The medium layer insulation has a certain oxidative degradation,but the crystalline structure is still improved after the moderate condition. The crystalline form of the outer layer insulation has been improved under the equivalent testing condition. Therefore,it is expected that the rest of retired cables still have the potential to reuse in long-term actual operation condition.