Abstract: Some single mineral experiments were carried out to study the influences of Fe3 , Cu2 , Pb2 , Mg2 on the floatation behaviors of fine cassiterite with sodium oleate as a collector. The results demonstrated that Fe3 , Cu2 , Mg2 three metal ions could reduce the recovery of cassiterite during the pH range from 2 to 12. Pb2 had a positive effect on the flotation of cassiterite when the pH=2~7.5, but a negative effect when the pH=7.5~12. Contact angle measurements indicated that Fe3 , Cu2 , Mg2 hindered sodium oleate from adsorbing onto the surfaces of cassiterite, Pb2 enhanced the hydrophobicity of cassiterite. The solution chemistry analysis revealed that the main components that acted as depressants in Fe3 solution were Fe3 and Fe(OH)3(s) when pH=2~3 and pH=3~12, respectively. And in Pb2 solution, Pb2 and PbOH were the main components that activated cassiterite.