Abstract: After preoxidation, the sample of tin ore or tungsten molybdenum ore was fused at 1 100 ℃ for 10 min using Li₂B₄O₇, NH₄NO₃ and LiBr as flux, oxidant and release agent respectively. The melt sheet was prepared after cooling. XRFS was applied to the determination of 16 components, i.e. Sn, W, Mo, As, Pb, Zn, Sb, Cu, Al₂O₃, SiO₂, Fe₂O₃, MnO, TiO₂, CaO, P₂O₅, SO₃ in the melt sheet. Ta₂O₅ was used as internal standard. Theoretical coefficient method was used to correct matrix effect. Detection limits of the 16 components ranged from 50 to 155 μg·g^-1. The proposed method was applied to the analysis of tin ore sample, giving results in consistency with the known values and values of RSDs (n=10) of determined values were in the range of 0.15%-1.2%.