When　single-phase　grounding　fault　occurs　in　resonance-grounding　system,　the　similarity　of　zero-sequence　transient　current　waveform　between　two　healthy　feeders　is　higher　than　that　between　fault　and　healthy　feeders.　The　former　is　related　mainly　to　the　line-earth　capacitance.　The　ratio　between　two　equivalent　line-earth　capacitances　is　adopted　in　the　stretching　transformation　of　zero-sequence　transient　current　waveform　to　improve　the　similarity　between　waveforms　and　the　margin　of　faulty　line　detection.　The　Euclidean　distance　between　the　phase-plane　trajectory　of　the　zero-sequence　transient　current　waveform　after　stretching　transformation　and　a　definite　point　is　calculated　based　on　the　sectional　phase-plane　analysis.　The　Euclidean　distances　of　sectional　phase-planes　are　applied　to　form　a　characteristic　matrix　to　represent　the　amplitude　and　polarity　information　of　the　zero-sequence　transient　current　waveform,　to　which　the　fuzzy　K-means　clustering　is　then　applied　for　detecting　the　faulty　feeder.　The　proposed　method　is　verified　by　simulations　in　different　conditions,　such　as　noise　interference,　arc-grounding　fault,　asynchronous　sampling,　varied　time　window　size,　etc.　The　simulative　results　demonstrate　its　higher　adaptability,　reliability　and　accuracy.