Monochromatic X-ray excitation X-ray fluorescence spectrometry was developed as a new SI traceable method (primary method of measurement). For the validation of the method, the certified reference materials such as FeCr alloys and sediments were analyzed. The evaluation of the uncertainties was carried out. The analytical results were in good agreement with the certified values within the uncertainties. Schematic drawing of the system and typical spectra are shown in Fig. (a) and (b) respectively. This method is non-destructive, and is used for various reliable measurements.