The nonlinear dynamic buffeting response with large deformation often occurs under the action of strong wind，which will always lead to wind flashover of power network and the wind damage of supporting towers. In order to reveal the formation mechanism of wind effect on transmission lines under the action of strong wind，this paper takes the typical two-span transmission lines-insulators as the research object，and studies on the wind deflection displacement of insulators and the reaction response of towers to the spatial supports at the end of insulators. Based on the cable structure mechanics，the nonlinear solution of the static average wind deviation state is analyzed，and the changes of dynamic characteristics such as mode and aerodynamic damping of the system under wind deviation are investigated. The expressions of the influence line function and modal participation coefficient of the response are derived，and the calculation method of linear dynamic response in time domain is proposed. According to the theory of wind engineering，the frequency domain expressions of background component and resonance component of fluctuating wind vibration response are given. A typical example is used to analyze and compare with the results of nonlinear finite element model.The results show that the three-dimensional vibration time/frequency domain theoretical model and the parameter calculation method proposed in this paper have sufficient engineering efficiency and accuracy. The study provides a theoretical basis and calculation method for revealing the damage mechanism of transmission line wind disaster and improving the wind-resistant design of transmission line structure.