A　probe　that　can　efficiently　detect　harmful　Cr(III)　and　Cr(VI)　at　the　same　time　is　urgently　needed.　In　aqueous　solution,　Cr(III)　and　Cr(VI)　are　in　the　form　of　the　cation　(Cr3+)　and　anions　(CrO42-,　HCrO4-,　or　Cr2O72-),　respectively.　Owning　to　their　opposite　charge,　it　is　a　great　challenge　to　develop　a　two-in-one　probe　for　Cr　detection.　Here,　we　report　an　amino-functionalized　YF3:Eu3+　fluorescent　probe　that　can　successfully　detect　both　Cr3+　and　Cr2O72-　with　good　selectivity.　The　surface　amino　groups　can　enhance　the　adsorption　affinity　of　both　Cr3+　and　Cr2O72-　ions　by　forming　coordination　bonds　and　electrostatic　attraction,　respectively.　As　a　result,　the　detection　limits　of　Cr3+　and　Cr2O72-　ions　are　determined　to　be　as　low　as　1.88　mu　M　and　1.34　mu　M,　respectively.　Finally,　the　amino-functionalized　YF3:Eu3+　is　also　successfully　applied　to　detect　Cr3+　and　Cr2O72-　in　practical　rain　water　and　tap　water　samples.