Abstract: It is conventionally difficult to obtain metallic lithium with ultra low Na/K content, to which the molten salt extraction is therefore suggested as a pioneer process to remove Na/K and relevant experiments. The thermodynamic analysis showed that K can react with both LiCl and Li2Cl, but Na can only react with Li2Cl, when using high-purity LiCl as extractant 923 K. So, removing Na/K from Li by molten salt extraction process is theoretically feasible. Furthermore, the experimental results also revealed that the molten salt extraction an effective way to remove Na and K, especially the K from metallic lithium, which is basically in conformity to the thermodynamic analysis.