The iron core of the dry power transformer adopts high permeability and high-quality grain oriented cold bonded silicon steel sheet 45° full oblique step joint. The core adopts special square tube pulling plate structure, the core column is bound with insulation tape, and the surface of the core is coated with special resin to prevent moisture and rust, which effectively reduces no-load loss, no-load current and core noise. Is a kind of electrical strength, mechanical strength, high dry transformer. It is an excellent product for urban power grid transformation, especially suitable for high-rise buildings, airports, power stations, commercial centers and other important places requiring fire prevention, explosion-proof and moisture-proof.