To　improve　the　sensitivity　of　permanent　faults　identification　for　three-phase　reclosure　after　a　single-phase-to-ground　fault,　a　three-phase　adaptive　reclosure　method　for　transmission　lines　with　shunt　reactors　was　developed　using　free　oscillation　frequency　estimation　of　shunt　reactors　currents　to　distinguish　transient　faults　and　permanent　faults.　There　is　free　oscillation　process　caused　by　the　energy　stored　in　distributed　capacitances　of　the　line　and　the　inductances　of　the　shunt　reactor　after　the　fault　takes　places　and　breakers　of　three　phases　open　at　two　ends.　The　free　oscillation　frequency　of　shunt　reactor　zero　modal　current　was　calculated　using　the　least　square　matrix　pencil　method　(LSMPM).　For　transient　faults,　the　frequency　is　equal　to　the　nature　frequency　of　zero　modal　networks　of　the　transmission　lines.　While　for　permanent　faults,　the　frequency　is　equal　to　the　arithmetic　average　of　nature　frequency　of　zero　modal　networks　and　that　of　aerial　modal　networks　of　the　transmission　lines.　So　calculating　the　oscillation　frequency　can　distinguish　permanent　faults　from　transient　faults.　EMTP　simulation　results　show　that　the　proposed　scheme　is　correct　and　valid,　and　its　performance　is　not　influenced　by　fault　position　and　transition　resistance.　©　2013　Chinese　Society　for　Electrical　Engineering.