Abstract: Local overheating is a common hidden defect in distribution lines, which is difficult to detect through visual inspection and can easily evolve into faults, reduce power supply reliability. This article will combine practical operation and maintenance experience to introduce the principle and characteristics of infrared thermal imaging technology. Based on the characteristics of infrared thermal imaging in the diagnosis of defects in distribution lines, the situation of overheating defects in distribution lines will be analyzed, and the important role of infrared thermal imaging technology in the diagnosis of defects in distribution lines will be explained in detail, in order to provide reference for the operation and maintenance of distribution lines.