Abstract: HVDC GIL with the advantages of large transmission capacity, small footprint and high reliability has a wide application prospect in the special geographical environment. However, the accumulated gas-solid interface charge and the existence of metal particles in GIL are essential factors which lead to the electric field distortion and even the surface flashover and thus limit the development of DC GIL. In this paper, we summarize and review the related research progress in surface charge accumulation mechanism and suppression methods, metal particles in GIL, surface flashover characteristics, application of eco-friendly gases in DC GIL, HVDC GIL manufacturing and testing, and key technologies for developing UHVDC GIL. The paper provides a reference to the design and development of DC GIL equipment.