The existing single-end fault location method of an all-parallel AT traction network has the problems of low sensitivity of fault section identification and the fact that second traveling wave head is easily affected by the fault point refraction and reflection. Thus a single-end fault location method based on the high-frequency energy ratio of the current traveling wave is proposed. First, the attenuation characteristics of the auto-transformer winding-to-ground capacitance on high-frequency components are analyzed. The difference in the high-frequency energy amplitude of fault current traveling waves in adjacent lines is demonstrated. An energy ratio difference criterion is established, and the fault section is localized using this difference criterion. Then, it analyzes the propagation characteristics of the traveling wave in the fault section of the all-parallel AT traction network, and reveals that the terminal bus traveling wave of the reverse direction current has the obvious singularity of the fault mutation. Finally, a fault location method based on the inverse direction current traveling wave is proposed. The precise location of the fault is determined by accurately calibrating the arrival time of the initial wave head and the second wave head of the traveling wave. Simulation results show that the proposed method can accurately recognize weak fault characteristics in a noisy environment, and improve the accuracy of fault location in an all-parallel AT traction network.