Abstract: To address the issues of low sensitivity in fault section identification and difficulty in identifying the second traveling wave head in single-ended fault location in existing all-parallel AT traction network (APATTN), a new fault location method based on the dominant characteristic quantities is proposed. Firstly, the boundary characteristics of the auto-transformer are analyzed, demonstrating the feasibility of using the dominant frequency difference criterion to identify fault sections. Then, based on the parallel structure of the up-and-down lines in the APATTN, the relationship between the current traveling wave mutation amplitude and the number of outgoing lines at both ends of the bus is analyzed. The dominant traveling wave head on each of the up-and-down lines is identified according to the principle of maximum mutation amplitude. Finally, a fault location method based on the dominant traveling wave head time difference in the APATTN is proposed. The precise fault point location can be achieved by utilizing the fixed mapping relationship between the dominant traveling wave head time difference and the fault distance. Simulation results show that the proposed method can be adopted to sensitively identify fault sections and accurately locate fault points without needing to identify the second traveling wave head, which is easily affected by transition resistance.