Abstract: A great number of fluorite ores occur in karst cavities of Yingshan formation of the Ordovician in Xiker outcrop in western Keping uplift of Tarim basin. In this paper, the mineral assemblages and occurrences and the geochemical features of fluorite and calcite as rare earth elements in the fluorite ore cavities are studied, and the fluorite ore evolution and ore?forming fluid source are discussed. It is recognized that the minerals found in the fluorite ore cavities are continuous products of the same hydrothermal fluid system in different evolutionary stages, and the magma thermal fluids of the Early Permian upwelling along the early formed faults have constructive modification effects on the reservoirs in this area