Abstract: A Fe-Ni-Si-B amorphous coatings was prepared by laser cladding on the substrate 45 carbon steel with a 5 kW continuous CO₂ laser.The phases, microstructure and the forming conditions of the amorphous coatings had been studied using X-ray diffractometer and transmission electron microscope.The results show the addition form of the boron iron is better than the B powder during the synthesis of the amorphous coatings.The glass forming ability of the alloy increases with increasing Si content and reaches maximum when it reaches 16 at.%.Si can protect the other components from oxidation and burning when it acts as a major composition in the alloys.The laser scanning velocity has influences on composition homogeneity and cooling rate of the melting pool under the given laser power and beam diameter.Amorphous alloys an be developed when the laser power is 4800 W and the scanning velocity reaches 3500 mm/min.