Abstract: In order to analyze the cause of the collapse of a 220 kV line tower, wind data of nearby meteorological stations, distribution and usage of the accident tower and the formation conditions of micro-topography and micro-meteorology of the location are investigated. The bearing capacity of the accident tower is verified and analyzed by using the full stress calculation theory. The results show that the tower is seriously overloaded due to the accidental strong wind caused by extreme weather and Canyon effect, which leads to the collapse of the line tower. In order to prevent such failures, it is proposed to adopt a differentiated design scheme in the special section, the square stay wire scheme can be used to reinforce the old tower, and the meteorological data monitoring should be strengthened in the accident prone section.