During the flotation process of fluorite, NH+4 and F- in the slurry have important effects on fluorite’s flotability of fluorite. At present, the research about the effects of inevitable cations on floatation mainly focus on the activation or inhibition mechanism of metal cations, but there is less research about the effect of the complex cation (NH+4) and the anion (F-) on the adsorption mechanism of sodium oleate to fluorite. Therefore, the action mechanism of NH+4 and F- on fluorite flotation by sodium oleate is studied in this paper by means of infrared spectroscopy analysis, combined with the flotation experiment of pure fluorite, Zeta potential and solution chemical calculation. The results show that NH+4 has a strong activation effect on fluorite and increases the recovery rate of fluorite under acidic condition, and when the pH value is 6, the recovery of fluorite increased to about 94% at different NH+4 concentrations. However, under alkaline conditions, NH+4 had a certain inhibitory effect on fluorite flotation, and the recovery rate decreased gradually with the increase of pH value. But F- inhibits fluorite to some extent, when the pH value is 6, the inhibitory effect of different F- concentrations is significantly enhanced, resulting in a decrease of fluorite recovery. However, under alkaline conditions, F- has little influence on the flotability of fluorite. The action mechanism is that the adsorption of the cation (NH+4) and F- dissociated from fluorite surface in solution form NH4F under acidic conditions to improve the electropositivity of fluorite surface, and enhance the adsorption between fluorite surface andmonomer, dimer and acidmolecule-ion association of oleic; while under alkaline conditions, the hydrolysis of NH+4 results in the formation of NH3·H2O, which reduces the positive electrical properties and leads to the weakening of the adsorption of sodium oleate on the fluorite surface. F- inhibits the dissociation of F- on fluorite surface, thus inhibiting the chemisorption of oleate acid ion on fluorite surface. FT-IR analysis results show that the chemisorption occurred between sodium oleate and fluorite surface. NH+4 had a strong activation effect on fluorite surface under acidic conditions because the characteristic peaks of —CH3, —CH2—, —COO- are red-shifted and their peak intensity is enhanced, showing a strong chemisorption effect. However, under alkaline conditions, only the characteristic peak of —CH2— appears red shift, and the intensity of the characteristic peak is weakened, indicating that under weak alkali conditions, the chemisorption of NH+4 on the fluorite surface is weak and inhibited the adsorption. When F- is added, only the antisymmetric expansion vibration peak of —CH3 appears and no red shift of the peak position has occurred. Therefore, no chemisorption of any group on the fluorite surface occurs after the addition of F-, which inhibits the flotability of fluorite.