Abstract: Transient enclosure voltage（TEV） generated during switching of disconnector in ultra high voltage（UHV） gas insulated switchgear（GIS） on influences of high amplitude,steep wave,wide bandwidth and other transient characteristics had been becoming more prominent,and may affecte the safety of operating personnel touched with GIS and normal operation of GIS monitoring devices.This paper relied on two test circuits of UHV GIS in 1 000 kV UHV AC test base of State Grid in Wuhan,carried out experimental studies of TEV characteristics.Experimental conditions comprised a number of wiring layouts,such as disconnector switching with fast and slow speeds,test circuits at load side in pre-charge or no pre-charge DC voltage,branch bus with different lengths and disconnector switching with replacement directions etc.A total of 2 940 times of experiments during opening and closing of disconnector and TEV simultaneous measuring of multiple points had been carried out.By a large number of TEV measurement results of statistical analysis,the TEV waveform characteristics of 1 000 kV UHV GIS were obtained,including full waveform characters of TEV,pulse numbers,full waveform durations,single pulse waveform characters,frequency components,single pulse waveform durations,amplitude rising and TEV amplitude characters influence in pre-charge or no pre-charge DC voltage,different branch bus lengths,replacement disconnector switching directions.In further,correlations of TEV and striking voltages,and VFTO were statistically analyzed.Through a series of experimental research,the paper obtained the TEV waveform characteristics of UHV GIS,and the results have provided the basis for further study on TEV modeling and simulation,development of standards and security protection etc.