Iron based nanocrystalline alloy is composed of iron, silicon, boron, niobium, copper ,etc.When annealed above crystallization temperature, fe-based amorphous alloy containing Cu and Nb will form very fine grain structure, the grain size is only 10-35 nanometers, this amorphous alloy after special crystallization annealing and the formation of crystalline materials called nanocrystalline alloy. Nanocrystalline material with high saturation magnetic induction intensity, high permeability, low coercive force, low loss and good stability, excellent properties and wear resistance of high strength willfulness, as in the metal soft magnetic material which has the best performance/cost ratio of nanocrystalline alloy material, can replace silicon steel, permalloy and ferrite is in the high frequency transformer, transformer, inductance components ideal material. Jinjing Nanocrystalline cores has been considered as THE finest material for transformer making.