Abstract: Five main components in blast furnace slag including SiO2,CaO,MgO,Al2O3 and S,were determined simultaneously by using the polarized energy dispersion X-ray fluoresence spectrometer.The secondary target HOPG provided in the instrument was used in the determination.It took only 120 s for an analysis.The results obtained by this method were in consistency with the standard values of standard samples and with the known values of routin samples found by chemical methods.