1 Introduction Iron Based Nano crystalline Ribbon is composed of Fe, Si, B, Nb, and Cu etc. Iron based amorphous alloy including Cu and Nb element can be formed into crystallite with size in 10-20nm above crystallization temperature through particular annealing treatment. The crystallite material is defined as Nano crystalline alloy. 2 Application EMC common mode and differential mode filter inductor cores; switching-mode power supply transformer cores; current mutual sensor cores (zero sequence, leakage protection); Magnetic amplifier, spike killer core, saturable inductor core; 3 Feature High saturation flux density, high permeability, low coercivity, Low loss, good stability, high strength and corrosion resistance, can replace silicon steel, permalloy and ferrite as ideal material for transformer, mutual inductor, its components, has the highest PQ ratio.