The invention discloses a current monitoring warning device for an overhead transmission line. The current monitoring warning device comprises a current transformer for acquiring the current of the overhead transmission line, a data acquisition module for acquiring current information of the overhead transmission line, a data processing module for processing the current information, a data concentrator for storing the current information processed by the data processing module, a wireless communication module and an online energy fetching device. The online energy fetching device is connected with the data acquisition module, the data processing module, the data concentrator and the wireless communication module and supplies power for the same. The hollow coil type current transformer is adopted, and the problems that a traditional electromagnetic induction type current transformer is prone to magnetic saturation, insulation is difficult and cost is high are solved; the advantages of being wide in input, stable and reliable of the suspension type online energy fetching device are utilized, an external power source is omitted, and the device is easy to install and free of maintenance.