This paper is aimed at the problem that the typical wall bushings with high and low voltage shielding of40.5kV switchgear appear partial discharge and surface discharge under working conditions. Ansys Workbench andother software are used for electric field calculation and problem analysis. Two structural optimization schemes areproposed. The cause of the initial discharge at the narrow fillet of copper surface is analyzed in the insulation test.The parameterized modeling optimization method is adopted. The length and radius of the shield of high voltage andearthing is taken as variables

and the repeated iteration is carried out in a certain range. Taking into considerationthe optimization scheme of high and low voltage shields for wall bushings

a design is verified by a test. And then afurther design of fully shielded structure for HV shield is designed. The parameters of these two structures are com-pared

and engineering suggestions are given in combination with production practice. The simulation and test re-sults show that shield optimization structure can reduce the maximum field strength of the surface of copper bar andthe outer surface of epoxy to 4.5kV/mm and 2.6kV/mm respectively. The high voltage full shielding structure reduc-es the overall field strength of the through wall bushing to 2.37kV/mm by eliminating the umbrella group near theground shield and reducing the thickness of the epoxy properly. It provides the engineering basis for the design of the wall bushing.