The embodiment of the invention discloses a fault line selection method and a device thereof for an earth neutral system, wherein the fault line selection method for the earth neutral system comprises the following steps: by using current transformers which are respectively arranged on each feeder line in at least one group of feeder lines to be monitored in the earth neutral system, acquiring induced current of the current on each feeder line in the at least one group of feeder lines to be monitored, wherein, each group of feeder lines to be monitored in the earth neutral system comprise three feeder lines respectively connected to three phases of output of the earth neutral system; respectively analyzing the components of the acquired induced current of the current on each feeder line; and indicating the corresponding feeder line containing resistive current in the current components of the analyzed induced current as an earth fault feeder line. The technical scheme of the inventioncan select the feeder line with earth fault in the earth neutral system relatively quickly and accurately, thereby being favorable to immediate repair and reducing the occurrence probability of accident.