Although a variety of functional materials have been developed for the separation target ions, most of them suffer from sluggish uptake of ions and deficient selectivity. Herein, a nanocomposite electroactive film with a sandwich-like structure was facilely prepared by intercalating conductive polyaniline (PANI) into the interlayer of montmorillonite (MMT) with layered structure for rapid and selective separation of Pb2+ ions. This MMT/ PANI nanocomposite film exhibited an extreme Pb2+ ion uptake rate (1422.67 ?g?(g?s)-1), which exceeded those of conventional adsorbents by 2 to 4 orders of magnitude. Meanwhile, trace Pb2+ ions at ppb level in the wastewater were quantitatively detected by employing the MMT/PANI nanocomposite electroactive film based on its strong affinity towards Pb2+ ions. It was confirmed that the rapid and selective Pb2+ ion uptake/release by the MMT/PANI composite film was achieved via the directional proton migration powered by the electrochemical redox of the intercalated PANI, the superfast ion transport in atomically interlamellar ion transport path and the ultra-affinity ion recognition of ion capture sites on MMT layer. It is expected that such an MMT/ PANI composite film could be a promising alternative of conventional materials for separating and detecting of Pb2+ ions in wastewater.