Power frequency overvoltage poses a major safety risk to 500 kV transmission lines in ice-prone areas. Taking a 500 kV AC power transmission and transformation project in western China as an example, the line model is built by PSCAD software. Based on the line model, the generation principle of power frequency overvoltage under single-phase ground (SPG) fault and the suppression mechanism of shunt reactor are analyzed. Then the power frequency overvoltage of grounding fault under different icing line length, icing thickness and various capacity shunt reactor access is calculated respectively. The simulation’s findings indicate that: The power frequency overvoltage increases with the increase of the length of the icing line, but it is less affected by icing thickness; installing a shunt reactor can successfully reduce the amplitude of power frequency voltage.