The power loss of ground wire, produced by the magnetic coupling between phase line and ground wire, is becoming a more and more important parameter for economical operation of the power network. There are a variety of measures to reduce the power loss, such as graded insulation and ground wire transposition. An example of UHV transmission line is presented in this paper to investigate the characteristics of induced electromotive force of ground wire and power loss under different phase sequences and conductor transposition modes. It is pointed out that the power loss can be reduced to a minimum by negative phase sequence and reverse transposition of conductor, as well as graded insulation and transposition of ground wire.