The invention relates to a traction power supply network tail end voltage boosting device with a power fusing function and a method of the device. The device includes a multiple voltage reduction module and a power-fusing current-converting module; the multiple voltage reduction module is connected into two power supply arm power sources of the tail end of a traction power supply network and includes two single-phase multi-winding transformers of the same structure which are correspondingly connected into the two power supply arm power sources respectively through connection switches; the power-fusing current-converting module is used for performing energy conversion on the two power supply arm power sources and includes a plurality of current conversion sub modules; one set of voltage is connected into two input sides of each current conversion sub module through corresponding secondary windings of the two single-phase multi-winding transformers, so that energy conversion can be performed; and through controlling the switch-on of the current conversion sub modules, output voltage can be boosted, and power fusion of the two power supply arms can be performed. According to the method of the invention, the voltage of the tail end of the traction power supply network can be stabilized and boosted through controlling the power-fusing current-converting module. The device and the method of the invention have the advantages of simple structure, low cost, power fusion and train power network resonance suppression, and can boost the voltage of the tail end of the traction power supply network.