The oil-immersed transformer core is made of cold-rolled silicon steel sheet and the iron core frame is vacuum-annealed to improve the electromagnetic performance. The windings are made of corrugated oil passages. The transformer tank is composed of corrugated walls, and the surface is electrostatically sprayed with dust, and the paint film is firm. The corrugated fins not only have a cooling function but also have a "breathing" function. The elasticity of the corrugated radiator can compensate for the change of the volume of the transformer oil caused by the temperature rise and fall. No oil change is required during the normal life period, which reduces the maintenance of the transformer and improves the safety and reliability of the grid operation.