This paper introduces the special operation environment and requirements of GIL withhigh voltage or ultrahigh voltage（UHV）in the cross-river tunnel and the integrated pipe corridor in large cities. The common operation failures of GIL are summarized. The design requirements and scheme of GIL reliability structure are described in terms of insulation

seal

electrical contact

busbar and shell support. The essentials of GIL applicability design are discussed from the aspects of convenient field disassembly and assembly

characteristics monitoring

fault finding and treatment

etc. The concept of partitioned operation of long GIL with enclosed isolation switch and the design concepts of reliability and application of local discharge monitoring system are proposed. In order to ensure the reliability of GIL operation

the importance of manufacturing quality control is emphasized

which may provide reference for GIL’s design

manufacture and operation.