Currently used fault phase selector components are compared and their characteristics and shortcomings are pointed out. In particular， such problems as the weak power phase selector， sensitivity fit and impedance identification mismatch under the condition of system oscillation are analyzed in detail. An improved fault phase selector scheme is presented， in which the complementary judgment of the two impendence components at the same zone is used to solve the mismatch problem. The results of EMTP digital simulation and dynamic experiment indicate that the new scheme has appreciably improved the capabilities of the original scheme. In particular， for the phase selector under the condition of power swing， the impedance identification mismatch problem can be completely overcome and the fault phase selector result is free from the effect of power swing.