Aiming at the deficiency of the measurement accuracy of the wave velocity in the current traveling wave ranging method and the defect of the detection algorithm of the wave head, by analyzing the changing law of traveling wave speed with frequency, the frequency range when the wave speed is stable is derived, so as to eliminate the influence of the wave velocity on the ranging result. On the basis of studying the relationship between the arrival time of the traveling wave of the highvoltage direct current (HVDC) transmission line fault and the specific instantaneous amplitude of the traveling wave, the mechanism of the instantaneous amplitude affecting the traveling wave location is analyzed, and a fault location method of the transmission line based on the instantaneous amplitude is proposed. The iterative method forms a timeamplitude diagram of the highfrequency current fault signal. According to the timeamplitude diagram, the wave head time and the specific instantaneous amplitude at that time are determined to form a HVDC transmission line fault location algorithm. MATLAB/Simulink simulation results show that the relative error of this method is within 03%, and compared with the positioning method of Hilbert Huang transform, this method has higher positioning accuracy and is basically not affected by fault distance and transition resistance.