The invention discloses a resonance grounding system single-phase earth fault section positioning method; the method comprises the following steps: forming adaptive criteria according to an inherent amplitude ratio between an inductance current and a capacitance current in a low frequency network, thus effectively determining a fault section; using an excessive compensation effect of an arc extinguishing coil on a low frequency external signal to obtain an inductance current circulation loop that highlights the fault point and an arc extinguishing coil installation portion. The method uses a SOP excellent waveform modulation capability to actively inject the low frequency signal, thus omitting extra investment of a signal injector used by a conventional signal injection method, and enlarging the injection signal capacity; the method is simple in principle, high in reliability, and not affected by a transition resistance, system operation modes and line lengths.