Abstract: The Mössbauer spectroscopy, small angle x-ray scattering (SAXS) and x-ray diffraction were employed to investigate the structural relaxation for amorphous Fe_73.5Cu₁Nb₃Si_13.5B₉ alloy. The annealing temperature dependence of the M ssbauer parameters and the small angle scattering intensity were presented and discussed. The results show that the thermal treatment involves a series of variations in the Fe atomic environment, domain structure and electron density. The annealing leads to a decrease of free volumes and an increase of wide domains oriented parallel to the long axis and a perpendicular anisotropy induced by the preferential crystallization of the surface. By SAXS it is observed that the Cu clusters form around 400℃. The appearance of the phase boundaries between the crystalline phase and the amorphous matrix upon crystallization is associated with less inhomogenities ie electron density.