Abstract: In order to explore the water aging characteristics of wet submarine cables under long-term seawater operation environment, long-term operation resistance to water tree cross-linked polyethylene (WTR-XLPE)insulation, an accelerated water aging test of water-resistant tree insulation materials for submarine cables was carried out. The breakdown characteristics of insulation samples after aging were tested by step stress method, and the residual dielectric strength of cable samples at the end of their service life after water accelerated aging was evaluated. The test results showed that the LH4201R water-resistant tree insulation material of the test cable had passed the breakdown field strength required by the standard after accelerated water aging test, so the waterresistant tree insulation material can be suitable for theoffshore wind power array cables.