The ultra high voltage（UHV）DC test base of the state grid corporation of China plays an important role in Chinese UHVDC transmission technology development.One of the tasks of this test base is to carry out research on the electromagnetic environment impact of UHVDC power transmission and provide technical support for the construction and operation of the UHVDC demonstration project.The 1 200 kV bipolar UHVDC voltage generator is the main source of the experimental lines in the test base

and its corona control is very important for the guarantee of the quality of electromagnetic environmental research.The corona level of the generator depends on its surface electric field.This paper presents a FEM simulation model for the generator and investigates the characteristics of the surface electric field intensity distribution of the generator.Based on the simulation analysis

some shielding measures are provided to optimize the electric field distribution. The results of the research are applied in the design and construction of the bipolar UHVDC generator.The operation result shows that the corona level of the generator is effectively controlled.