Abstract: During the X-ray inspection of the "three span" section of the transmission line, it was found that the internal steel core of the strain clamp of the heat-resistant conductor of the 110 kV Guanfu Line 1 and 2 was broken. Fangshan Power Supply Company and State Grid Beijing Electric Power Research Institute have carried out the work of tension clamp disassembly analysis, steel core failure analysis, crimping process recurrence test, etc. According to the analysis, the reason for the steel core fracture is that the crimping process (back pressure method) is not standardized, resulting in the longitudinal fracture of the steel core inside the tension clamp. Based on this, some suggestions are put forward to strengthen the hidden trouble detection and X-ray detection for the construction process of the heat-resistant conductor strain clamp in operation.