Abstract: Effect of carboxymethyl cellulose (CMC) in sodium oleate system on the flotation separation of apatite against dolomite in single mineral experiments was investigated in this study, and its mechanism was further studied through infrared spectrum analysis and Zeta potential analysis. The recovery of apatite and dolomite both attained 90% with 100 mg/L sodium oleate, and changed to 95.52% and 4.72%, respectively with addition of 5 mg/L CMC. As a result, the efficient separation of apatite against dolomite was achieved. The adsorption of sodium oleate on the surface of apatite and dolomite was a physical process. CMC was connected with Mg²⁺ on the surface of dolomite like a "bridge", and hindered the adsorption of sodium oleate on the surface of dolomite. The ability of CMC to hinder the adsorption of sodium oleate on the surface of apatite was extremely limited, so CMC would not influence the flotation of apatite. The Zeta potential results indicated that the surface potential of apatite had a slight negative shift with the increase of CMC concentration, while that of dolomite had a significantly negative shift, indicating that CMC can prevent the adsorption of sodium oleate on the surface of dolomite, but cannot prevent the adsorption of sodium oleate on the surface of apatite.