Efficient　removal　of　Pb2+　from　wastewater　is　of　great　significance　for　human　health　and　environmental　protection.　However,　Pb2+　capture　from　complex　wastewater　is　still　very　challenging　due　to　the　strong　competition　with　other　metal　ions.　Herein,　the　highly　selective　removal　of　Pb2+　has　been　achieved　by　a　cluster-based　material,　namely　H1.03Ba2.485(H2O)15[Zn2Sb12(mu　3-O)8(mu　4-O)3(tta)6]&　sdot;8H2O　(H4tta　=　tartaric　acid)　(FJSM-BZA).　FJSM-BZA　exhibits　high　adsorption　capacity　(199.29　+/-　5.86　mg/g)　and　fast　kinetic　response　(kinetic　equilibrium　is　reached　in　20　min)　for　Pb2+.　In　particular,　even　in　the　presence　of　competing　ions　Mn2+,　Co2+,　Ni2+,　Cu2+,　and　Cd2+,　FJSM-BZA　maintains　excellent　selectivity　for　Pb2+　with　removal　rate　much　higher　than　that　of　other　metal　ions.　The　material　after　Pb2+　adsorption　could　be　regenerated　by　a　simple　elution　method.　The　unprecedented　single-crystal-to-single-crystal　(SC　to　SC)　structural　transformations　during　Pb2+　adsorption　and　elution　are　unveiled,　which　helps　directly　elucidate　the　distinctive　mechanisms　of　ion　exchange　between　Ba2+　and　Pb2+.　It　is　revealed　that　the　strong　coordination　interactions　of　the　active　carboxyl　groups　at　the　periphery　of　the　cluster　with　Pb2+　ions　are　the　intrinsic　driving　forces　for　the　ion-exchange.　This　work　highlights　the　design　and　synthesis　of　crystalline　metal-oxo　cluster-based　materials　for　highly　selective　removal　of　Pb2+.