Variation of ice thickness with altitude results in non-uniform icing distribution on conductor lines. The non-uniform icing and ice-shedding are defined and numerical simulation method for the dynamic response of tower-line system after ice-shedding from conductor with non-uniform ice are carried out with additional element method. The finite element models of typical isolated and multi-spans tower-line coupling systems of 500kV quad-bundle transmission lines are established, and the dynamic responses of the tower-line systems after ice-shedding from the conductor lines with non-uniform icing are numerically simulated. The dynamic response characteristics of the tower-line systems, including the stress distribution and load impact factor of the towers, the maximum reaction force at the connecting points, longitudinal unbalanced tension and jump height of the conductor lines after ice-shedding, vary with structural, icing and ice-shedding parameters are analyzed. The strength of towers under extreme conditions is also analyzed. The obtained results provide important instructions for the design of tower heads in the transmission lines in ice zones.