Abstract: Based on the existing approximate method, the prediction of the most adverse input direction of a transmission tower-line system under far-field seismic excitations is carried out. Based on practical engineering, the finite element model of a transmission tower-line system is established in ABAQUS. In order to verify the applicability of the approximate method, seven typical far-field seismic ground motions are selected. The response history analysis of a transmission tower-line system under different input directions is carried out, and the results are compared with those obtained by the approximate method. The comparison shows that the approximate method has good accuracy and reduces the computational cost of response history analysis. The most adverse input direction of far-field seismic ground motion obtained by the approximate method can basically determine the most adverse response of the transmission tower-line system. At the same time, the most adverse input directions of different ground motions are different, and the vibration response of a transmission tower-line system varies with the input direction of ground motion.