We have produced very low Fe-dose (10⁸-10⁹ Fe/cm²) implanted Si samples. A new method of Ultraviolet Fluorescence Spectra (UFS) measurements has been used to determine the contents of Fe on the surfaces of Fe-implanted samples. We find that the Fe-impurities have their own ultraviolet fluorescent peak wavelength at room temperature and their characteristic spectral peak intensities are proportional to the Fe-doses (Fe-concentrations) in Fe implanted Si samples. This method is very sensitive, efficient and nondestructive for testing the Fe contamination on silicon. Some SOI (Silicon on Insulator) wafers and VLSI chips were evaluated with the UFS method. The results indicate that the UFS method is able to measure the very low Fe-contamination. The limit is below (10⁸-10⁹) Fe/cm² or (10¹³-10¹⁴) Fe/cm³ in Si samples.