When single-phase to ground fault happens in non-effectively earthed systems, in order to select the fault line more accurately, this paper puts forward the concept that relative intensity of the transient signal (Q). And based on this, a new method processing nonlinear and the non-stationary single named Hilbert-Huang transform (HHT) was combined with the steady-state zero sequence current method, named a new line selection method which synthesized the transient and steady state quantity. The method makes full use of transient and steady-state line information, to make up for the shortage of the previous method which using single criterion to detect fault line. At last, it was showed that this method is not affected by the fault initial phase Angle and grounding resistance by MATLAB, and also its accuracy and feasibility have been verified.