Abstract: In order to improve the security and stability of power grid,a single-phase reclosing mode is usually adopted in the extra-high voltage（EHV）power system.As there is no non-simultaneous problem after a single-phase of the power line tripout,the traditional single-phase reclosing logic and its realization method is simple.On January 2,2011,apermanent fault of500 kV Yihuan line 1occurred in the Northeast Power Grid.The single-phase reclosing failed,and the short circuit current failed to break,resulting in breaker body damage.Then the failure protection acted and the bus jumped,expanding the power grid accident.In order to avoid similar accident to happen again,the network model characteristics and fault mechanism are analyzed in depth.A short-circuit current characteristic factor for reflecting the line fault is proposed.The threshold of the short-circuit current characteristic factor is defined,which can identify the existing problems of reclosure in the power network.Finally,the reclosure schemes that should be adopted are studied when the grid structure satisfies the characteristics.The effectiveness of the schemes is verified by the operation test in the actual power grid.