The present invention relates to a transformer with good heat-dissipation performance. The transformer comprises a main body, an oil conservator, a heat-dissipation mechanism and a rust-removing mechanism. The rust-removing mechanism comprises a moving plate, a motor, a transmission component, a lifting sleeve tube, a first spraying nozzle, a moving frame, a guiding rod, two driving wheels and twoguiding rails. The transmission component comprises an annular gear, a bevel gear, a first transmission shaft, a second transmission shaft, a first driving wheel, a second driving wheel, a first driven wheel, a second driven wheel, a first transmission belt, a second transmission belt and a driving block. The heat-dissipation mechanism comprises a water tank, a shell, a first water pipe, a secondwater pipe, a water pump and at least two second spraying nozzles. According to the transformer with the good heat-dissipation performance, by providing the rust-removing mechanism, the first spraying nozzle can be driven to move around the main body, and then the first spraying nozzle sprays a rust remover on the transformer, so that the rusting rate of the transformer is slowed down; and by providing the heat-dissipation mechanism, the heat dissipation rate of the oil conservator is improved, and thus the heat-dissipation performance of the transformer is improved.