Abstract: During the preparation of manganese metal steel plates for X-ray fluorescence spectrometry （XRF） analysis by dilution melting using pure iron as the flux, the mass of the steel plate after melting was found to be less than the total mass of the sample and flux before melting, indicating mass loss during the melting process. 20.000 0 g of high-purity iron particles （flux） were placed at the bottom of the corundum crucible, followed by the addition of 8.000 0 g of the sample, which was then covered with another 20.000 0 g of high-purity iron particles. The corundum crucible was placed inside a graphite crucible and the steel plate was prepared in the high-frequency vacuum melting furnace. The composition and structure of the attachments at the bottom of the melting corundum crucible were analyzed using XRF and X-ray diffraction （XRD）. As shown by the results, the attachments primarily consisted of Fe₃O₄ （magnetite）, FeO·Al₂O₃ spinel, and MnO-containing composite spinel. During melting, the oxides in the sample and flux reacted with the crucible, forming products that adhered to the crucible surface rather than entered the steel plate, thereby causing the mass loss of the steel plate. This reaction altered the ratio of the sample to the flux （dilution ratio） in the steel plate, so mass correction was needed. The calibration results showed the linear relationship between the calibrated mass fraction of manganese and fluorescence intensity was kept in the range of 89.851%−99.831%. After mass correction, the determined values of elemental manganese in manganese nitride, manganese metal, and its oxidation products were basically consistent with the theoretical values, with absolute errors less than 0.30%, significantly improving the accuracy of the analysis.