The oil immersed reactor is mainly composed of iron core, winding and its insulation, oil tank, bushing, cooling device and protection device. The structure of oil immersed reactor is shown in the figure. The core structure of single-phase reactor is single core column and two side pillars, and the core structure of three-phase reactor is pin shaped core column and coil iron clip structure. The reactor core column is composed of iron core cake and air gap cushion block. The core cake is made of high-quality cold-rolled silicon steel sheets. The core cake adopts radial radial radial lamination to make the magnetic flux enter into the side of the silicon steel sheet, and the preferred longitudinal magnetization direction of the silicon steel sheet is parallel to the axis of the core column, so as to reduce the eddy current loss caused by the edge effect when the magnetic line leaves and enters the core cake. Many iron core cakes are made of polished round porcelain pillars or marble round cushion blocks. The iron core cakes and gaps are alternately stacked and tightened with anti magnetic screw. In the alternating magnetic field, the electromagnetic force causes vibration and noise between the iron core cakes, so the pressing device of the iron core reactor is very important. The discus and iron clip should be grounded, and the iron clip and side column should be bound with epoxy glass fiber adhesive tape.