The invention relates to the technical field of electric systems and power electrons, in particular to a power-failure-free direct-current deicing device. According to the power-failure-free direct-current deicing device, on the basis that normal power supplying is not influenced, a direct deicing current is superimposed on a deicing line, the deicing current is allowed to circulate only in the deicing line, and the important devices such as a main transformer in a substation are not interfered. The power-failure-free direct-current deicing device is installed inside a transformer substation on one side of the line, and all the operations are completed in the substation on one side of the line. The power-failure-free direct-current deicing device achieves the power-failure-free deicing function, and besides, has the advantages of being high in deicing efficiency, small in capacity and the like.