Extra high voltage substation is an important part of the whole project locates in high altitude area, so corona audible noise exists around the operation equipment, mainly concentrated in the bundle conductor in the power station. This research on the split form and surface electric field intensity distribution of bundle conductor has a certain degree of theoretical and practical engineering application value. In this paper, an analysis of the classic formula illuminates the conductor split form, conductor diameter, bundle spacing and other factors how to affect the largest surface electric field intensity of the conductor. On this basis, we take a typical extra high voltage substation conductor as the research object. The three-dimensional model of the actual power station has been established with application of finite element simulation method in accordance with actual structure, and a preliminary calculation of surface electric field intensity also been obtained. According to the results, we analyze the reasons cause the serious corona. Then we design three-split conductor instead of two-split one, and make a comparative analysis between the two different forms. According to the three-split form mentioned above, the conductor diameter and bundle spacing are optimized. The research on the electrical field calculation and split form of bundle conductor provides references for the design of substation, and has practical value for the reduction of corona noise.