Chain-of-spherical magnetic iron UFP have been prepared by irradiating Fe (CO)5/SF6 system with a CW CO2 laser. During nucleation, the Fe vapour was let to pass through a orientated DC magnetic field, so as to improve anisotropy of the powder. It was indicated by comparing the two different conditions of nucleation that laser pyrolysis may acquire a higher pressure range of preparation and higher efficiency than gas evaporation.