The phenomenon of off-line discharge of the pantograph is greatly affected by the weather, especially when the contact net is covered by ice. Based on the generation mechanism of pantograph offline discharge, this paper establishes an equivalent circuit model of pantograph offline discharge when contact wire is icing, and calculates and analyzes its discharge voltage and current characteristics. First, verify the correctness of the built model by comparing the calculation results of the model with the measurement results; then apply the model to analyze the discharge conditions generated when the contact wire is covered with ice layers of different thicknesses. By comparing with the results of off-line discharge of pantograph under normal conditions, the influence of contact wire icing on the phenomenon of off-line discharge of pantograph and net is analyzed, and feasibility opinions are put forward for trains traveling through ice.