In order to explore the impact of uneven icing on the modal characteristics of high-voltage transmission towers, a model of a 110 kV wine cup type high-voltage transmission tower is established using the finite element method. Modal analysis was performed under different icing conditions, including no icing, partial structural icing, and three-phase conductor icing. The results show that the natural vibration frequency decreases slightly under partial structural icing, while it decreases significantly when three-phase conductor icing is considered. This is mainly caused by the increase in mass and changes in mass distribution due to icing. Additionally, icing also leads to changes in the vibration mode of the tower. This study validates the effectiveness of finite element simulation in predicting the dynamic response of transmission towers and provides important parameters for the design and maintenance of transmission lines.