Abstract: An ice damage fault trip event of 500 kV line is analyzed. The cold wave causes the temperature to drop sharply, and the rain and snow freezing causes the line to freeze rapidly; Then, affected by the warm and humid air flow, the temperature rose rapidly in a short time, and the uneven de-icing and jumping of the conductor led to the insufficient safety distance between phases, resulting in the interphase fault. After patrol inspection and defect elimination, the maintenance personnel will reduce the impact of extreme weather on the operation line and improve the safety level of the operation line through measures such as anti-ice transformation of the line, strengthening the extreme weather warning, and improving the emergency repair ability.