Parallel　transmission　lines　under　fault　can　be　decoupled　into　common　component　net　and　differential　component　net.　For　the　differential　component　net　is　only　composed　by　parallel　lines　part　and　its　bus　voltages　are　zero,　the　voltage　distributions　along　differential　component　net　can　be　calculated　by　each　terminal　current.　The　novel　time-domain　fault　location　algorithm　is　founded　by　voltage　distributions　from　both　terminals　have　the　least　difference　at　the　fault　point.　The　synchronization　is　achieved　by　searching　the　minimal　value　of　locating　criterion　function,　which　is　calculated　by　fixing　one　terminal　data　and　moving　another　terminal　data　within　a　setting　time.　The　proposed　algorithm　needs　a　very　short　data-window,　any　segment　of　fault　data　front　transient　to　steady　state　can　be　used　to　locate　faults,　and　no　voltage　data　is　needed.　With　distributed　parameter　model,　simulations　show　that　the　locating　errors　are　less　than　0.1　km,　and　the　fault　types　and　fault　resistances　have　no　effect　on　locating　accuracy.　(C)　2005　Elsevier　Ltd.　All　rights　reserved.