When　single-phase　grounding　fault　occurs　in　resonant　earthed　system,　the　transient　zero-sequence　current　waveform　difference　between　faulty　line　and　healthy　line　is　bigger　than　that　between　healthy　lines,　based　on　which,　an　approach　of　faulty　line　detection　is　put　forward.　The　wavelet　packet　decomposition,　reconstruction　and　information　enhancement　are　carried　out　for　the　fault　transient　zero-sequence　current　waveform　of　each　line　and　the　amount　of　time　windows　is　determined　for　each　frequency　band　according　to　its　size.　The　distribution　feature　matrixes　of　each　time　window　and　its　relative　entropy　are　calculated　and　then　used　to　recognize　the　waveform　difference　degree　among　the　same　time　window　of　different　lines.　The　faulty　line　is　then　picked　out　by　the　equal　weight　voting　from　the　candidate　faulty　lines　selected　during　waveform　difference　recognition　for　different　time　windows.　Substantial　simulative　results　show　its　accuracy　and　reliability.