The material composed of a definite amount of nanocrystalline phase α-Fe(Si) with a double-phase structure was produced by laser irradiation on the amorphous Fe735Cu1Nb3Si135B9 alloy with a laser power ranging from 50 to 300W, scanning speed 20mm/s, laser beam spot 20mm. Hyperfine structures of the nanocrystallized samples were analyzed by Mssbauer spectra. Experimental result shows that after the CO2 laser irradiated on the amorphous allo y Fe735Cu1Nb3Si135B 9, its hyperfine magnetic field dist ribution transformed from a single peak to double peaks with the change of laser power. When irradiated at a high laser power, it formed a double-peak structure and the peaks moved to a high field position. Nanocrystallization of amorphous Fe7 35Cu1Nb3Si135B9 ir radiated by a higher laser power produces fou r hyperfine structures, i.e. two primary crystal phases with relatively small hy perfine magnetic field and two nanocrystalline phases with a relatively large hy perfine magnetic field. The major crystal phase is the α-Fe(Si) phase of DO3 whose hyperfine magnetic field is comparatively larger (17—25MA/m).