With the rapid development of UHV power grid, the main electrical connection of UHV substation becomes more and more important to the safe and reliable operation of power grid. Therefore, the selection of suitable main electrical connection is a key work in the construction of UHV substations. According to the characteristics of Suzhou 1 000 kV UHV substation, he 500 kV main electrical connection scheme is analyzed in this paper. The techno-economic comparison between double-bus connection and two-thirds connection is carried out and the 500 kV main electrical connection of Suzhou UHV substation is suggested to adopt the double-bus connection, which not only could meet the requirements of the reliability of power grid, but also have some advantages of flexible scheduling, convenient expansion, small occupation of land and low investment.