±UHV (Ultra-high voltage) DC (direct current) wall bushing is an important equipment of UHV DC transmission system. It plays a key role in the economic transfer, flexible allocation and safe usage of power. In this paper, the methods of improving the electric field distribution and insulation construction optimization are explored. The choice of insulation materials is discussed. Some calculations are made about how to optimize and design the capacitor core and how to optimize the parameters of grading rings. The research results would provide useful reference for further design and development of UHV DC wall bushings.