Aiming at the characteristics of the un-effectively grounded systems that the zero-sequence current is non-stationary and nonlinear, a new fault line detection method based on empirical mode decomposition(EMD) and energy curve was proposed in this paper. The advantage of the EMD is its great adaptability, because EMD can decompose the signal according to the signal"s change regulation itself; The energy curve is better than the amplitude at the discrimination of the fault line and non-fault lines.Firstly, each of the zero-sequence current of fault lines were EMD treatment; then we can get the first-order Intrinsic Mode Function(IMF) and its energy curve; finally the fault line detection can be done by the phase of the first-order IMF and the size of the energy. The results of the simulation and experiment indicated that the method is reliable.