Aiming at addressing the issue of wind-induced vibrations in large-span T-shaped tangent transmission tower-line systems, the authors established a three-dimensional finite element model of both single tower (ST) systems and three-tower and four-line (TF) systems in this paper, which were verified by comparing with the existing literature. Based on these models, viscous damping vibration control technology was introduced, and numerical simulations were used to study the wind-induced vibration responses and damping effects of the ST model and the TF model. The results indicate that the finite element models accurately reflect the dynamic characteristics of the transmission towers, with an average error of 9.55% compared to the first five frequencies in the existing literature. Under wind-induced vibrations, the response of the ST model and TF model increased with height, with the dynamic amplification factor of the acceleration response at the top of the ST model exceeding eight times for models without control. However, the design of viscous dampers on the transmission towers effectively suppressed the dynamic response under wind-induced vibrations and reduced the response amplification trend along the height direction. The maximum wind-induced vibration control effects for the ST model and the TF model reached 76.49% and 77.81%, respectively, demonstrating that viscous dampers can significantly attenuate wind-induced vibration responses of such structural systems.