Ferromagnetic Fe73.5Cu1Nb3Si13.5B9 amorphous ribbon samples were exposed to CO2 laser irradiation with various powers (150 W,200 W,250 W,300 W) and the same scanning speed (20 mm/s) in order to produce nanocrystalline phase on the surface of amorphous Fe73.5Cu1Nb3Si13.5B9. The nanocrystallization of amorphous Fe73.5Cu1Nb3Si13.5B9 radiated by CO2 laser is studied by means of Mssbauer spectra (MS), transmitance electron microscope (TEM) and X-ray diffraction (XRD). The crystalline phase is α-Fe(Si),it has four hyperfine structure , and the size of which is about 10～20 nm; the nanocrystalline evenly distributes in the amorphous matrix to form the amorphous and crystalline composite structure. The amount of crystallization along with laser energy increases. The control of the nanocrystal phase quantity can be gotten with the control of the laser treatment process parameters.