The invention relates to a power transmission line lightning stroke or fault location method based on a Sobel energy spectrum, and belongs to the technical field of fault location. The power transmission line lightning stroke or fault location method based on the Sobel energy spectrum comprises the following steps that firstly power frequency components in transient waveforms of lightning stroke or other faults are removed, filtering is further carried out to obtain the transient waveforms, and then the Sobel energy spectrum of the transient waveforms is calculated by using Sobel operators. Onthe basis, a Sobel energy threshold value is calculated to distinguish noise from a target signal, and the starting time of the target signal is calibrated. When a line breaks down or suffers from lightning stroke, the time difference of transient signals arriving at signal measuring points can be calculated by calibrating the starting time of the transient signals measured at the transient signal measuring points at both ends separately, and the fault location can be carried out by using a double-end ranging formula. The positioning accuracy of the fault method provided by the power transmission line lightning stroke or fault location method based on the Sobel energy spectrum is less influenced by the fault transient waveforms, and strong noise resistance, higher positioning accuracy forlightning stroke and line faults and stronger robustness are achieved.