This　work　reported　an　unpresented　rare-earth-ion　bearing　metal-organic　framework　(MOF)　Y10(C8H4O4)6(CO3)3(OH)12　built　of　inorganic　slabs　as　structural　units.　Eu3+　has　been　introduced　into　the　lattice　of　Y10(C8H4O4)6(CO3)3(OH)12　to　make　it　optically　active.　Systematical　structural　analysis　combined　with　single　crystal　X-ray　diffraction　demonstrates　Eu3+　was　incorporated　into　the　lattice　of　Y10(C8H4O4)6(CO3)3(OH)12　endowing　the　MOF　with　promising　optical　activity.　Even　though　there　was　a　trace　amount　of　Eu3+　<　1%,　this　compound　displayed　excellent　luminescent　activity　with　quantum　efficiency　reaching　up　to　69%,　benefiting　from　the　inorganic　circumstance　of　Y3+/Eu3+　in　layered　structure.　The　concentration-dependent　electronic　transition　character　of　Eu3+　is　systematically　studied,　according　to　Judd-Ofelt　theory　normally　applicable　in　inorganic　compounds.　The　phase　analysis　and　optical　spectroscopy　study　result　reveal　that　the　local　crystallographic　circumstance　of　the　rare-earth　metal　ion　basically　remained　inactive　after　the　replacement　of　Y3+　by　Eu3+.　Benefiting　from　this　rigid　structure,　such　Eu3+-substituted　Y10(C8H4O4)6(CO3)3(OH)12　powder　exhibits　good　luminescence　probing　ability　toward　Fe3+　ion,　displaying　a　limit　detection　concentration　of　Fe3+　down　to　12.7　μM　in　aqueous　solution.　The　findings　here　confirm　Eu3+　is　not　only　an　environmental　probing　ion　but　could　also　serve　an　ideal　indicator　for　investigating　the　structure　change　and　properties　of　luminescent　MOFs　for　diverse　applications.　©　2019　American　Chemical　Society.