The combined reagents of sodium N-oleoylsarcosinate (SNOS) with metal ions (Ca(II), Mg(II), Cu(II), and Pb(II)) was employed to facilitate the separation of lepidolite from feldspar. The synergistic interaction mechanism of this combined reagent was systematically investigated via contact angle measurements, AFM, FTIR, species distribution calculations, and DFT calculations. The results suggested that Ca(II) exhibited the best selectivity for activating lepidolite flotation. SNOS was chemically adsorbed on the Ca(II)-activated lepidolite surface with an adsorption energy of -1248.91 kJ/mol while a lower adsorption energy of -598.84 kJ/mol of SNOS on Ca(II)-activated feldspar was calculated. Therefore, this combination of SNOS and Ca(II) is a promising reagent scheme for the efficient recovery of lithium from aluminosilicate ore.