The invention discloses a ground-wire-current-based method for identifying a fault location of a ground wire insulator of a power transmission line. The method comprises: S1, a line fault current monitoring device is installed at a ground downlead of an angle tower to carry out monitoring so as to obtain a current waveform signal in a ground wire; S2, preprocessing is carried out on the current waveform signal obtained at the S1 to obtain a current waveform signal without any ultra-high-frequency pulse interference; S3, time extraction processing is carried out on the current waveform signal obtained at the S2 to obtain data including a fault current waveform; S4, the data obtained at the S3 are analyzed to obtain a spectral signal characteristic; and S5, according to the spectral characteristic extracted at the S4 and signal amplitude information, a fault number and a fault location are determined. Therefore, information of a fault insulator is obtained timely and thus a fault is localized and found out timely, so that accident worsening is prevented.