The effect of carboxyl methyl cellulose (CMC) on the flotation separation of scheelite from calcite using sodium oleate as collector was studied in this work. The results of flotation tests indicated that CMC could selectively depress the flotation of calcite. However, the addition of calcite strongly strengthened the depressing effect of CMC on scheelite flotation. The addition of sodium carbonate could eliminate the adverse impact of calcite on the performance of CMC in scheelite flotation, and a concentrate with both high grade of WO3 and scheelite recovery could be achieved under CMC in the presence of sodium carbonate. Zeta potential results indicated that CMC adsorbed more strongly on calcite surface than that on scheelite surface, and the addition of CMC prevented the adsorption of the sodium oleate on the calcite surface.