Abstract: DC gas insulated switchgear/gas insulated transmission line (GIS/GIL) has the advantages of a compact size, high current capacity, and a broad range of applications, making it an important support for constructing new types of power systems and achieving dual carbon goals. However, despite the widespread application of gas-insulated equipment, surface discharge faults of insulators remain a primary cause of equipment failure. The two significant sources of these faults are the accumulation of charge on the insulator surface and the adsorption of metal particles or dust. We focus on the charge transport relationship at the gas-solid interface, revise the continuity equation for ion density in the insulating gas, and analyze the importance of electric field control. Furthemore, we summarize the research findings of scholars both domestically and internationally who have used technical means such as structural optimization of insulators, modification of bulk materials, and modification of surface materials to control interface charge, optimization of the surface electric field, and suppressions of dust adsorption. Additionally, we outline the key issues and significant technical challenges that remain to be addressed. For research on the structural optimization of insulators, it is necessary to identify the functional relationship between flashover voltage and the vector of the surface electric field and discharge path, based on accurate electric field simulation and advanced optimization algorithms, so as to determine the appropriate optimization target function. For the modification of the bulk and surface materials of insulators, the development of large-scale preparation processes for new types of modified materials and precise doping and stable coating technologies is required. Attention must be paid to the thermal stability and insulation performance of modified materials during long-term operation and a design method for high-viscosity, low-surface-energy coatings that ensure long-term reliable adhesion while inhibiting dust adhesion should be proposed. Effective solutions to the aforementioned issues can provide effective support for addressing the surface insulation problems of DC GIS/GIL.