The general expression of Lagrange nonlinear cable element is established firstly by using virtual work principle. On the basis of the theory, the specific expression of a two-node cable element having rotational degree of freedom is derived and the non-linear finite element model of multi-span transmission line for galloping analysis was established. In addition, the aerodynamic coefficient of iced conductor under different wind attack angle was obtained through computational fluid dynamics method. Based on the finite element model and aerodynamic characteristics of the iced conductor, the Runge-Kutta method was applied to carried out non-linear numerical simulation of iced conductor galloping and the Matlab program was compiled. The galloping of the multi-span transmission line crossing Hanjiang River was analyzed. The results indicate that the presented method can simulate the galloping process effectively and it can provide the basic references for further research of preventing galloping.