Abstract: The ferroboron alloy sample was melted with pre-oxidation fusion, and glass melt of the sample was prepared. XRFS was applied to the determination of 4 elements, i.e. boron, silicon, aluminum and phosphorus in the glass melt. The optimized conditions found were as follows:① the flux was potassium pyrosulfate; ② the dilution ratio of flux to sample was 40:1; ③ lithium carbonate and sodium nitrate were used as the oxidant; ④ the melting time of glass melt was 20 minutes. Linear relationships between values of fluorescence intensity and mass fraction of the 4 elements were kept in definite ranges, with lower limits of determination in the range of 0.006 8%-0.017 9%. Ferroboron standard sample was tested for 10 determinations, values of RSDs of determination values were in the range of 0.22%-3.9%. The proposed method was applied to the analysis of ferroboron alloy sample, giving results in consistency with the values obtained by wet process.