对输电铁塔主材断裂进行了失效分析，通过承载力计算，化学成分、常温和低温力学性能试验以及对失效塔材断口、金相组织分析，探讨并明确失效原因，提出防范措施。结果表明：塔材为低温脆断，而冲孔形成的微裂纹是导致塔材低温失效的主要原因。

Fracture of primary materials in transmission tower is analyzed, main conclusions of material failure are drawn and suggestions for improvement is put forward by analyzing bearing capacity, chemical properties, low-temperature tensile properties, fracture part of main material and microstructure of the main fracture material. The results show that main reason for material failure is low-temperature brittle fracture which is mainly caused by cracks in the process of punching.