The effects of Ca²⁺ and SO₄²⁻ on the flotation behaviour of fluorite with sodium oleate as a collector and the underlying mechanism by which these effects were investigated via micro-flotation experiments, solution chemistry calculations, and X-ray photoelectron spectroscopy. The results indicated that the addition of SO₄²⁻ and Ca²⁺ inhibited fluorite flotation and the inhibition effect was increased by the addition of pH. This was mainly due to the increase of the sulphate-containing components in the solution and the adsorption of SO₄²⁻ on the surface of fluorite. With the increase of pH, the alkalinity of the solution increases, OH^- and more SO₄²⁻ are further adsorbed on the fluorite surface, thereby reducing the recovery of fluorite flotation.