Abstract: In view of characteristics of DC component of transient zero-sequence current in fault lines is larger than that of normal lines when additional DC source system of mine power network occurrs single-phase earth fault, a fault line selection method of mine power network based on least-square matrix pencil algorithm and Romanovsky criterion was presented. The method uses least-square matrix pencil algorithm to extract DC component of transient zero-sequence current, and the DC component of each line is formed matrix. Then, it uses Romanovsky criterion to judge fault. If the absolute dispersion is larger than the critical dispersion, it is the line fault, the rejected data branch is the fault line, otherwise it is the buses fault. Simulation results show that the method is accurate，reliable with high adaptability.