Abstract: Very fast transient overvoltage（VFTO）,transient enclosure voltage（TEV） and electromagnetic interference（EMI） with steep wave-front and high amplitude are generated during switching of disconnector in gas insulated switchgear（GIS） with no-load short busbar.The transient voltages cause high stress on the insulation of GIS,equipment connected to GIS and electronic devices connected to GIS enclosure.And the operation of electronic devices is interfered by EMI.VFTO and associated effects have seriously affected the safety operation of equipment in GIS substations.To guide the equipment development and engineering design for ultra high voltage（UHV） transmission systems in China,the achieved results before 2009 on VFTO measurement,characteristics test,digital calculation and its impact on insulation were summarized in the paper.And the achievements on measurement and simulation of VFTO within UHV GIS by State Grid Corporation of China were described.Finally some subjects of VFTO in UHV GIS to be deeply studied were proposed.The transmitting characters and simulation model of VFTO should be emphasized,including the insulation properties and its mechanism under VFTO.All the achievements provide important reference to master thoroughly the characteristics of VFTO in UHV GIS and to guide the switching of GIS.