Abstract: The separation of fluorite and calcite is difficult, because there are Ca²⁺ active sites on the surface of fluorite and calcite, and the surface properties of the two minerals are similar. Through single mineral flotation test, adsorption amount measurement, Zeta potential measurement and chemical calculation of flotation solution, Fe³⁺ was introduced and mixed with sodium silicate to study the effect of the combined inhibitor on flotation separation of fluorite and calcite and its mechanism. Flotation test results show that, Fe- sodium silicate selectively inhibits the flotation of calcite compared with sodium silicate, and realizes the separation of the two minerals. The mechanism test results show that the Fe- sodium silicate polymer formed by Fe²⁺ and sodium silicate in solution and the hydrolyzed component Si(OH)₄ have strong adsorption on the surface of calcite, which hinders the further adsorption of sodium oleate and thus inhibits the flotation of calcite.