The article shows, that for organisation of safe and non-stop train handling at the railways, the monitoring of only one type of hardware (automation and remote control, track or power supply) is not enough. Complex monitoring of all infrastructure objects, that is based on the fundamental approaches, and one of them is risk management theory. For this very reason the selection of components and systems, that do not have a backup, and determination of its technical state is a key problem. The paper examines the organisation of the overhead system monitoring - from the quality of its operation the performance of all transportation facilities depends on. The article provides the analysis of known technical solutions for overhead system maintenance and monitoring organisation within railways of the Russian Federation, as well as international practices, taking into account national and foreign standards of this field. There is a description of a new method of overhead system technical state monitoring, based on complex approach to the measurements of those parameters, that can influence as on the characteristics of current-collecting, and on the assessment of the overhead catenary state. The method, suggested in the article, allows to diagnose such important events as: breaking of one or several cores of span wire; complete breaking of span cable and overhead conductor; impacts with overhead conductor; non-normative performance of weight-compensating gear; forces in the ropes of overhead catenary; rising of self-oscillations and vibrations in the span wire and overhead conductor, etc. Obviously, several parameters, registered by the designed system, allow to determine pre-failure conditions of overhead catenary. Modular method, suggested for building of monitoring system, allows a multi-purpose use of the data transfer channel, including for diagnostics data from the adjacent facilities, that significantly decreases capital investments into infrastructure. Experimentally confirmed, that for quality and efficient monitoring at one section its is necessary to install at least 6 diagnostics units, that transfer the monitoring results, using wireless channel, conforming to IEEE802.15. Organisation of the overhead system technical state monitoring structure is an important step to the creation of highly reliable devices for keeping the infrastructure objects fault-free, for providing the efficient operation of all railway complex, for decreasing the operation costs, reduction of the influence of human factor aspect, and it allows to change over to condition-based maintenance.