Abstract: In the fault identification of power transmission and transformation lines, identification and positioning are mainly carried out for single feature points without eliminating superimposed faults, resulting in inaccurate positioning results. Therefore, a design and research on the online fault location technology for power transmission and transformation lines based on UAV inspection is proposed. Firstly, the sensing range is determined by combining RTK, and edge points are marked within the range. According to the UAV inspection path and edge points, the fuzzy fault area of transmission lines is marked. Then, UAV inspection is adopted to extract feature points in the fuzzy fault area, and positioning is performed through synchronous identification of multiple feature points. Superimposed fault points are eliminated in the process, and real-time feature targets are output. Finally, the fault feature targets are locked hierarchically according to the set levels. Under the continuous operation of power transmission and transformation lines, online location is carried out based on the levels to complete the positioning task. Experimental results show that the fault location error of the proposed method is basically controlled below 0.4%, which meets the actual standard of expected positioning error; its accuracy and overall performance are superior to those of traditional methods.