The pantograph and catenary system, serving as the ‘throat’ for the energy supply of high-speed railways, inevitably experiences degradation due to catenary caused by ice accumulation when high-speed trains pass through areas with high relative humidity, low temperature, and high wind speeds. Therefore, starting from the mechanism of catenary icing, this paper develops a numerical simulation model for icing on catenary, based on key factors such as collision, capture, and freezing rates. It provides a detailed analysis of the icing formation process on high-speed railway catenary and studies the growth characteristics of ice mass and profile under different climatic conditions. By using meteorological data obtained from the line monitoring system, the model allows for timely and accurate monitoring of icing conditions, laying a theoretical foundation for research on anti-icing and de-icing technologies for the pantograph-catenary system. This can effectively prevent severe icing incidents and ensure high-speed railways’ safe and smooth operation.