The invention provides a device for dismounting a rusted nut on a sleeve of a power-distribution electric transducer. The device comprises a medium-frequency alternating-current generating device and U-shaped ferrite, wherein the medium-frequency alternating-current generating device is connected with the U-shaped ferrite through a current output cable; an induction coil is wound on the U-shaped ferrite; a strip-shaped ferrite is arranged at one side of the U-shaped ferrite; the strip-shaped ferrite is arranged in alternating-current magnetic fields for cutting alternating-current magnetic lines of force generated by the induction coil. According to the device provided by the invention, certain gap is formed between the rusted nut and a bolt by utilizing electromagnetic induction heating and the principle of heat expansion and cold contraction, so that the nut can be easily dismounted through a common wrench.