Abstract: Taking XLPE insulated cable as an example, the influence of the microstructure of the insulating medium on the movement of carriers under different electric fields was analyzed, and the electric field distribution in the insulating medium of AC/DC cables was discussed. In the comprehensive consideration of the coupling mechanism between the microscopic carrier and the trap, the main factors affecting insulation stability and cable operation stability were further discussed. Based on this situation, the main differences of AC/DC cables in the insulation and operating characteristics were summarized. The results showed that the different responses of microscopic carriers of cable insulation medium under power-frequency AC electric field and stable electric field determined the significant differences in the insulation and operating characteristics of AC/DC cable. Space charge was the most essential factor affecting the insulation characteristics of DC cable and partial discharge was the main factor affecting the insulation aging of AC cable, which provided a theoretical basis for different technical considerations in structural design and cable operation and maintenance of AC/DC cables insulation.