Composite bushing is used widely in ultra-high voltage（UHV）GIS due to its such advantages as anti-wetflashover

anti-explosion

light weight and low cost.In the development of composite bushing for UHV GIS

the problem of partial discharge exceeding standard is encountered.In this paper

it is confirmed by way of analysis of partial discharge phenomenon and laws as well as location of the partial discharge that the partial discharge occurs at the position of the composite hollow insulator corresponding to the internal shield system.Moreover

it is confirmed through electric field analysis that the defect of electric field distribution design of the shield system near the shield leads to partial discharge.The improvement of system of shield structure and optimization of electric field distribution keeps the maximum electric field intensity of the shed of the bushing reduce from 0.49 kV/mm to 0.26 kV/mm

which eliminates effectively the partial discharge and achieves perfect practical application.