Evaluation of the insulation status of in-service cross-linked polyethylene（XLPE） cable is very important for improving the reliability of distribution system. In this paper

8 unserviceable and 24 in-service 10 k V XLPE cables of different insulation status belonging to a power company were tested based on the polarization and depolarization current（PDC） method. Meanwhile

A and Q were used as characterization parameters

which can represent the dielectric traps inside band gap and discharge capacity during polarization process respectively. Finally

The Spearman’s correlation coefficient was used to establish the correlation between A/Q value and cable information

and the sensitivity and influence degree were calculated to judge the aging state of cables. The results show that the PDC method can be used not only for the whole cable insulation diagnosis

but also for the confirmation of local dampness and aging phenomenon. The urgency method based on the relationship between aging degrees and basic information

such as service year

load type

length and laying way can be adopted to find the potential high-risk aging cables. In conclusion

the PDC method is able to improve the cable maintenance efficiency and accuracy

and the insulation status of non-direct buried downtown long power cables should be paid more attention to in daily maintenance.