The increase in insulation failure rate of EHV/UHV GIS seriously threatens safe and stable operation of power system. The improvement of its insulation reliability has become a significant issue of widespread concern and urgent solution. In this paper

the key measures and research progress on improving the insulation reliability of EHV/UHV GIS are reviewed from the aspects of the causes and prevention measures of GIS discharge

true type test and design improvement

defect identification

monitoring and warning. In terms of product design

such factors as insufficient match between the design and process of EHV/UHV GIS

less consideration of process implementation

shipment and operation cause problems such as accumulation of foreign bodies on the surface of insulating spacer and breakage of closing resistors. In terms of the manufacturing process and inspection of parts

the less quality control and key components of GIS and the bottleneck problem coexists

and such static withstanding voltage test as power-frequency withstand voltage

partial discharge and impulse withstand voltage can detect insulation defects to a certain extent. However

there are blind spots in detecting latent defects

and the pertinence and sensitivity of insulation assessment need to be improved. In terms of live detection

the current GIS partial discharge on-line monitoring strategy has a low detection rate of insulation surface defects and the detection of episodic partial discharge is often neglected

which results in the low timeliness and accuracy of fault warning in operation. The success rate of fault warning can be improved effectively by using the detection technology combining episodic partial discharge

X-ray and highly sensitive components. Furthermore

it is necessary to promote the research on the mechanism of foreign body generation and discharge in life cycle

deepen the GIS insulation design and particle suppression technology and im-prove the effectiveness of insulation test on defect detection and

at the same time

accelerate the quality improvement and localization of key components of GIS

improve the fault warning capability of GIS and

on this basis

build the GIS health assessment capability in life cycle and improve insulation reliability of EHV/UHV GIS.