Abstract: Due to their unique chemical and physical properties, ionic liquids are recognized as a class of green and environmentally friendly diluents with great application prospects in the field of solvent extraction. In addition to their good solubility for extractants and extracted species, ionic liquid extraction systems often exhibit satisfactory performance through ion exchange mechanism. Taskspecific ionic liquids(TSILs) emerge as a kind of chemically modified ionic liquids, which possess dual functions of ionic liquids and ligands with specific chelating groups. TSILs can not only be used as diluents in the extraction process, but also serve as extractants for separation of metal ions. In the past two decades, TSILs have received extensive attention in the area of nuclear waste treatment. This review first introduces ionic liquids and TSILs focusing on their structural connections and differences. Then, a summary is offered to briefly evaluate the ionic liquids used for the extraction and separation of uranyl ions, thorium ions, lanthanides, and minor actinides, respectively. Finally, this review also provides the outlook of TSILs for lanthanide/actinide separation.