Abstract: Zinc oxide ore is often accompanied by clay minerals. In the flotation process, the fine clay particles are easy to coat with slime on the zinc oxide mineral surface, thereby seriously deteriorating the flotation of zinc oxide minerals. In this study, octadecyl amine (OCTA) was used as a collector to study the flotation behavior of a mixture of smithsonite and chlorite. The micro-flotation tests showed that the single minerals of smithsonite had a high flotation recovery, while the single mineral of chlorite exhibited poor floatability. However, the flotation recovery of smithsonite mixed with chlorite was significantly reduced. To improve the floatability of smithsonite mixed with chlorite, cetylpyridinium bromide (CPB) was introduced in the flotation process as a dispersant, which was compared with the traditional dispersant sodium hexametaphosphate (SHMP). It was found that CPB had better performance in strengthening the flotation of smithsonite than SHMP. By using Zeta potential measurements, SEM-EDS analysis and chemical calculations of the flotation system, the mechanism of CPB enhancing the separation of smithsonite and chlorite was revealed. CPB can effectively enhance the flotation separation of smithsonite from chlorite, which is attributed to its adsorption on the surface of chlorite, thereby preventing the fine particles of chlorite slime from coating the surface of smithsonite. These results show that the new dispersant CPB has potential application prospects in the flotation separation of smithsonite mixed ore.