Abstract: Aiming at the technical bottlenecks in the detection of heating defects of transmission lines, this paper systematically analyzes the technical principles and application efficiency of defect inspection by unmanned aerial vehicles (UAVs) equipped with infrared devices. By establishing a mathematical model of infrared radiation transmission, the influence mechanism of parameters such as detection distance, ambient temperature and atmospheric attenuation on temperature measurement accuracy is deduced. A mathematical model for optimizing UAV inspection parameters is constructed to realize the multi-objective optimization of flight altitude, shooting angle and cruising speed. A probabilistic statistical evaluation system for defect identification is established to quantitatively analyze the technical and economic performance of different detection methods. The research results show that the UAV infrared detection system is significantly superior to the traditional manual inspection method in terms of identification accuracy of heating defects, detection efficiency and safety performance, which provides an important technical support for the condition-based maintenance of transmission lines.