Abstract: The real-time running data of signal equipment was obtained by using multiple kinds of sensor technology, and transmitted by using wireless communication and network technologies. The paper introduced the Online Monitoring System for signal devices of metro. The System was with real-time monitoring functions to turnout, switch machine, active balise, the track circuit, signal equipment, power equipment and system. It was beneficial to remote real-time monitoring operation signal equipment, and facilitated the use, maintenance and fault diagnosis of equipment.