Abstract: For the determination of Zr in Zircon sand, the spectral line of Zr is mainly used. However, the spectral line of Zr Kα does not reach the saturation thickness for the fused bead, which leads to poor linearity and large errors in the results. The determination of ZrO₂, HfO₂, SiO₂, Al₂O₃, CaO, TiO₂, Fe₂O₃, MgO, Na₂O, Cr₂O₃, P₂O₅, and MnO in Zircon sand samples has been developed with fused bead by Wavelength Dispersive X-ray Fluorescence Spectrometer. In this article, a detailed description of the study for the selection of the Zr spectrum line is given. Through theoretical arithmetic, the saturation thickness of the Zr Kα is 6638 μm, which is far beyond the thickness of the fused bead of 2500 μm while the saturation thickness of the Zr Lα is only 20 μm, which is within the range of the bead. Therefore, the Zr Lα is much more suitable than Zr Kα, as mentioned in published articles. The RMS of Zr Kα is 1.03 while the RMS of Zr Lα is 0.39. The accuracy and the precision of the ZrO₂ are greatly improved. The respective saturation thickness for Hf Lα and Hf Lβ is 971 μm and 1444 μm. The Hf Lα₁ line is overlapped by the second line of Zr Kα, hence, the Hf Lβ line is selected as the analysing line. The mixed flux of Li₂B₄O₇ and LiBO₂, the proportion of the flux and sample and the temperature of the fused sample are all optimized. The matrix effect was corrected by the theoretical α coefficient and empirical coefficient. The calculated detection limits of the respective elements coincide with the measured results. The precision of the method (RSD) is 0.1%-10.9%. The results are in agreement with the certified values obtained by chemical methods, which showing that the measured spectral line determined through calculation of saturated thickness of Zr and Hf has certain feasibility.