Abstract: A wireless-node communication network was designed to detect single-phase-to-ground faults in railway automatic blocking and continuous transmission lines by combining S-injectionmethod with wireless nodes. The system makes use of automatic net-organization function and high fault- tolerant characteristic ofsensornetworks. It is composed ofa signal injection device, wirelessnodes, a wireless process unitat the switch station and an intelligent faultdetection system. Signals are injected on awireless node. The intelligent faultdetection system receives the detected results transmitted from thewireless node and locate the fault position. Determined by simulations, the power source is of constantcurrentand its frequency ranges from 220 to 320Hz. The sensors are arranged in twomodes: parallel and interleaving. These two modes both meet the requirement of reliability for information transmission, but the reliability of the former is as triple as thatof the latter. The locating precision of the system is adjustable according to application.