Abstract: The electrical treeing of heterogeneous insulation composed of cross-linked polyethylene (XLPE) cable body and accessories seriously threatens the safe operation of cables and accessories. In order to explore the AC/DC electrical tree and partial discharge characteristics in XLPE-silicone rubber (SIR) heterogeneous insulation at different temperatures, the electrical tree experiments and partial discharge detection under AC and DC voltages are carried out on XLPE-SIR samples at 30, 50 and 70℃, respectively. The results show that the characteristics of partial discharge are closely related to the development stage of the electrical tree, and the discharge change rate has the strongest correlation. The interface of the heterogeneous insulation impedes the development of the electrical tree. It is also found that the breakdown paths are different under AC and DC voltages, which is presumed to be related to the non-ideal contact at the interface, and the differences in charge distribution and partial discharge near the interface. Besides, it is found that the increase of temperature can promote the initiation and growth of electrical tree, and has a significant effect on the morphology of AC trees. This research can provide a theoretical basis for the monitoring and evaluation of insulation aging state at the accessories of high-voltage AC/DC XLPE cables.