The utility model provides a device for remotely monitoring a transformer iron core current online in real time. The device comprises a leakage current sensor (1) for collecting transformer iron core current analog signals and alarm signals. A data acquisition cabinet is used to convert the current analog signals into digital signals and to upload the digital signals and the alarm signals to a monitoring management device (4) via a serial port device (3). The device conducts comprehensive, visual and real time monitoring and intelligent analysis of the operation status of a reactor iron core, provides more precise, timely and complete information, improves work efficiency, reduces labor intensity of workers, provides effective technical support for transformer condition-based maintenance at the same time, and can improve the level of safety and reliability and the capability of disaster prevention and mitigation of a power grid.