Fluorite is an important industrial raw material with a wide range of uses. For the determination of CaF in fluorite, wet chemical analysis is usually used, but there are problems such as complex operation and long analysis time. The flux used for melting samples in X-ray fluorescence spectroscopy (XRF) is usually lithium tetraborate, sodium tetraborate, etc. This article attempts to use sodium metaphosphate (NaPO) as a flux and determine the content of CaF in fluorite by melting sample preparation XRF method, eliminating the particle size effect and mineral effect of the sample. The method is simple and the results are accurate.