Gas-insulated metal-enclosed switchgear (GIS) has been widely used in power system,and the safe and reliable operation of the GIS are very important.Restrained by the device structure and circuit inductance,the on-site lightning impulse (LI) withstand test is difficult to be carried out in the GIS substation,especially in the ultra-high voltage (UHV) GIS substation.In this paper,the present situation of GIS impulse test is analyzed.And then the influence factors of insulation defect detecting using impulse test such as waveform parameters,polarity and interval time between two impulse tests are elaborated.Finally,based on the moveable gas-insulated impulse voltage test complete equipment,the on-site standard lightning impulse test is applied successfully in 1000 kV Nanjing substation and 1000 kV Suzhou substation.