ACSR fatigue failure is the process of injury continuous accumulation and strength gradual decline. The fatigue strength of the ACSR is declining with the number of dynamic load increasing. When the residual strength of the strand is equal to the dynamic bending stress, the ACSR strands are broken. Therefore, the research on residual strength of EHV transmission line has the important significant on fatigue breakdown and injury of ACSR. Based on the non-linear strength degradation model, the structural properties and loading characteristics of EHV transmission lines are considered in order to derive the ACSR residual strength model. And the model parameters are calculated according to the conservative S-N curve of ACSR formulated by CIGRE. The feasibility of the residual strength model is proved through the analysis on different examples. The research shows that the relationship between the degradation degree of conductor strength and loading times is non-linear. The strength decay rates are different with different loadings. The amount of conductor strength attenuation is positively correlated with the intensity of conductor vibration as well as the duration of vibration; with the same load, the decay rate of ACSR strength is increasing with loading times increasing.