The knowledge of tailing slurry’s heavy metal elementalry grade is important in mineral flotation processing. It can improve mineral utilization andreduce environmental pollution. X-ray fluorescence spectroscopy is an effective technology for determining heavy metal elements. Compton scattering internal standard is commonly used in X-ray fluorescence spectroscopy quantitation for geological samples. However, for thin film samples, the Compton scattering peak will be affected by the filter. However, it wasn’t easy to measure the Compton scattering intensity of the sample directly because it was tightly attached to the filter.In this paper, the filter’s influence on the sample’s Compton scattering intensity was discussed for the tailing slurry’s thin film sample after filtration, and the Compton scattering intensity of the thin film sample was corrected. The experimental results show that the intensity of the Compton scattering peak increases linearly with the increase of the thickness of the polypropylene filterin the thickness range of 0.34～3.06 mm.Therefore, the linear relationship between the total Compton scattering intensity obtained by the detector and the filter thickness was established, and the scattering peak intensity was the true Compton scattering peak intensity of the sample when the filter thickness was 0. Afterwards, Monte Carlo simulated the Compton scattering of samples with no filter and samples with different filter thicknesses. The results showed that the corrected Compton scattering intensity was the same as that of the sample without filter, with a relative deviation of only 0.41%. The ratio of the corrected Compton scattering intensity to the uncorrected Compton scattering peak were 91.31% and 89.91%, compared through experiments and simulations when the thickness ofthe polypropylene filter is 0.34 mm, which has a good consistency. Finally, the standard curves of elements were established and corrected by the uncorrected and corrected Compton scattering internal standards after six standard materials were measured experimentally.Quantitative analysis of the Cu, Zn and Pb elements in the two tailings slurry showed that the uncorrected Compton internal standard correction increased the relative deviation of some elementsby 3.18% to 9.00% compared with the ICP-OES results before correction. However, the relative error between the quantitative result of the corrected Compton internal standard method. Moreover, the ICP-OES result was between 1.14% and 11.15%, which was reduced by 0.30% to 8.97% before the correction.