Abstract: This is an essay in the field of mineral processing engineering. Fluorite and calcite are calcium-bearing minerals with similar physical and chemical properties. Flotation separation of the two minerals has always been one of the difficult problems in the ore processing field. The effect of Fe³⁺ on flotation separation of fluorite and calcite in sodium silicate system and its mechanism was studied by flotation test, adsorption amount measurement, Zeta potential measurement and chemical calculation of flotation solution. The flotation test results show that, compared with sodium silicate, the addition of Fe³⁺ has a stronger inhibition effect on the flotation of calcite, but little effect on the flotation of fluorite, which can achieve the selective separation of the two minerals. The results of adsorption amount measurement, Zeta potential measurement and chemical calculation of flotation solution showed that after introducing Fe³⁺ into the sodium silicate system, Fe-(OH)_X, Fe-sodium silicate polymer and Si(OH)₄ were selectively adsorbed on the surface of calcite, which hindered the further adsorption of sodium oleate as collector, thus achieving the separation of fluorite and calcite.