Variation in ice thickness with altitude results in a non-uniform icing distribution on conductors. This study defines non-uniform icing and ice-shedding conditions and employs an additional element method to numerically simulate the dynamic response of tower-line systems after ice-shedding from conductors with non-uniform icing. Finite element models of typical isolated and multi-span tower-line coupling systems for 500 kV quad-bundle transmission lines are established, and their dynamic responses are analyzed. The variation patterns of characteristic parameters, including load impact factors, maximum reaction forces at connection points, longitudinal unbalanced tension, and de-icing jump height, with respect to line span, elevation difference ratio, and icing thickness are examined under varying structural, icing, and ice-shedding parameters. The strength of towers under extreme conditions is also analyzed. The obtained results provide critical guidance for the design of transmission tower heads in ice-prone regions.