In order to get closer to the actual path condition of transmission line and deeply understand the seismic response of transmission line under large span, large elevation difference and inconsistent excitation, a large span section of ± 500 kV DC transmission line is selected, and the refined finite element models with four tower and three span lines are established for seismic response analysis. The results show that the ground wire and conductor significantly reduces the natural frequency of the tower. The cross-over tower is obviously constrained by the ground wire and conductor, and the peak displacement of the tower top is very small. The member stress of ground wire peak, cross arm and tower body are all within the elastic range. The peak tension force of cross-over span conductor is much higher than the design value, but still less than the breaking force, and the value is related to the length of anchor tower cross arm. The influence of traveling wave excitation on the displacement response is irregular, and it has little effect on the member stress and conductor tension force.