Abstract: Ionic liquids are considered to have promising applications in the extraction and separation in nuclear fuel reprocessing processes. Conventional extractants exhibit superior extractive performance in ionic liquids than in conventional solvent systems, thus the role of ionic liquids themselves is worth investigating. This paper reviews the interactions between metal ions/complexes and the cations/anions of ionic liquids in the extraction and separation of lanthanides and actinides studied by molecular dynamics simulations and quantum chemical calculations.