Abstract: The converter station is one of the core parts of UHVDC power transmission project. When the system is running, the electric field on the surface of the equipment inside the converter station has strict requirements to ensure that there is no corona. In this paper, the finite element simulation model is established based on the operation conditions of DC projects with different spherical electrodes as the research objects. The corresponding halo field strength under the halo voltage of different electrode structures is obtained, and the prediction curve of halo voltage and halo field strength of typical spherical and ring electrodes in plain area is obtained, which provides support for the design of hardware structure and the selection of spherical radius. At the same time, it also provides an important reference for improving the reliability of other equipment in the converter station and the equipment on the transmission line.