As discharge failures caused by problems such as pollution and cracking of transmission facilities have constantly threatened the safety of the transmission network, in this paper, discharge ultraviolet detection technology was first studied. Then, the Photomultiplier Tube (PMT) was used as the detector to design the discharge ultraviolet detection scheme. An ultraviolet detection and localization method for the Unmanned Aerial Vehicle (UAV) inspection of power line discharge was proposed. The PMT was driven by the steering of the steering gear to perform multi-angle detection, the current detection position and detection angle were recorded, and the preliminary positioning coordinates of the discharge point were obtained using the direction-finding cross-positioning method. In order to accurately locate the discharge point, n sets of data were solved to obtain the preliminary positioning coordinates of n(n-1)/2 discharge points. The preliminary positioning coordinates of the discharge point were then removed from the abnormal point and imported into the K-means clustering algorithm. A second solution was applied to obtain the exact coordinates of the discharge point. In the experiment, to test the relationship between the PMT detection angle and discharge ultraviolet signal, θ=90° was selected as the steering angle of the steering gear. Conducting discharge patrol experiments at 18 m, 30 m, and 50 m showed that the positioning error of discharge point are within 9.0%. The experimental results show that the method can meet the need for rapid location of the discharge point when the UAV patrols the power line.