The flotation performances of styrene phosphonic acid(SPA) to synthetic(Ce,La)_2O_3(REO), calcium fluorite(CaF_2) and fluorapatite(Ca_5F(PO_4)_3) were investigated by flotation tests, flotation of synthetic mixed mineral, the surface adsorption capacity and the polarizing microscopy to solve the flotation separation problem of rare earth oxides from roasted concentrate. The flotation test results indicated that compared with CaF_2 and Ca_5F(PO_4)_3, SPA exhibited superior collecting performance to direct flotation recovery of REO and floated out above 90% REO at pH 3–6. However, the collecting ability of SPA to CaF_2 and Ca_5F(PO_4)_3 was extremely weak and the highest recovery was only 20% at pH 2–11. The flotation of synthetic mixed mineral showed that SPA was a good collector reagent for flotation of synthetic REO at pH 5, so REO, CaF_2 and Ca_5F(PO_4)_3 could be separated from roasted concentrate by using SPA as a collector. The surface adsorption capacity tests and polarizing microscopy results confirmed that SPA was adsorbed on REO surface, while CaF_2 and Ca_5F(PO_4)_3 were not. The adsorption mechanism of SPA to synthetic REO was studied by solution chemistry analysis of collector, the ζ-potential tests, infrared spectroscopy and X-ray photoelectron spectroscopy(XPS) analyses. The results indicated that SPA was physically adsorbed onto REO surface, which exhibited excellent flotation selectivity to REO against CaF_2 and Ca_5F(PO_4)_3. The flotation performances of styrene phosphonic acid (SPA) to synthetic (Ce, La) _2O_3 (REO), calcium fluorite (CaF_2) and fluorapatite (Ca_5F (PO_4) _3) were investigated by flotation tests, flotation of synthetic mixed mineral, the surface adsorption capacity and the polarizing microscopy to solve the flotation separation problem of rare earth oxides from roasted concentrate. The flotation test results indicated that compared with CaF_2 and Ca_5F (PO_4) _3, SPA showed superior collecting performance to direct flotation recovery of REO and floated out above 90% REO at pH 3-6. However, the collecting ability of SPA to CaF_2 and Ca_5F (PO_4) _3 was extremely weak and the highest recovery was only 20% at pH 2-11. The flotation of synthetic mixed mineral that that SPA was a good collector reagent for flotation of synthetic REO at pH 5, so REO, CaF_2 and Ca_5F (PO_4) _3 could be separated from roasted concentrate by using SPA as a collector. The surface adsorption capacity tests and polarizing microscopy results confirmed that SPA was adsorbed on REO surface, while CaF_2 and Ca_5F (PO_4) _3 were not. The adsorption mechanism of SPA to synthetic REO was studied by solution chemistry analysis of collector, the ζ-potential tests, infrared spectroscopy and X- The results indicated that SPA was physically adsorbed onto REO surface, which exhibited excellent flotation selectivity to REO against CaF_2 and Ca_5F (PO_4) _3.