Abstract: When the cross-sectional power supply of heavy-load railways exceeds the load limits in an area or the load current is relatively high in case of a high traffic density, the feeder protection device of traction substations would fail to distinguish an overload state and an short circuit state at the end of the contact network,resulting in misoperation of overload protection. In response to such a safety hazard, it is proposed to use the optical fiber composite protection line for the contact network of Shuohuang Railway so as to achieve data exchange between different intelligent devices based on the IEC 61850 communication standard. The intelligent device of the traction substation enables to collect data information from adjacent traction substations as well as the section post and AT post on both sides, and correctly identify the operating status of a sectional load, the short circuit status at the end of the contact network and the normal operating status, such that it is to adjust the overload protection and overcurrent protection settings when a section is in a load state, which enables the overload protection not to malfunction and offer support for the normal operation of electrified railways.