The problem of the faulty line selection with the arc suppression coil(ASC) has existed for a long time.On the basis of analyzing the relationships between the ASC admittance and the admittances of lines,including the faulty line and non-faulty lines,the calculation of the b parameter is presented,in which the state of the ASC is changed during the single-ground existing for the faulty line selection by adjusting its inductance.The value of b for the faulty line is much greater than that for non-faulty lines in both the direct ground and the ground with the resistance.The proposed method is verified with the simulation and is applied to the projection.It is proven that the proposed method is with the high reliability.