The　feasibility　of　using　CaF2:Eu3+　powders　as　a　luminescent　probe　to　detect　Cr2O7　2-　ions　was　studied　in　this　article.　A　series　of　CaF2:Eu3+　powders　with　different　Eu3+　substitution　rates　was　prepared　by　a　modified　sol-gel　method,　ending　with　a　sintering　procedure　of　the　xerogel.　The　luminescent　probing　ability　of　CaF2:Eu3+　powders　on　Cr2O7　2-　ions　was　studied　for　the　first　time.　It　is　found　that　the　CaF2:10%Eu3+　powder　exhibits　a　sensitive　response　to　Cr2O7　2-　ions,　with　an　obvious　quenching　of　the　Eu3+　luminescence　with　increasing　concentration　of　Cr2O7　2-　ions　in　the　aqueous　solution.　The　investigation　of　the　selective　luminescence　quenching　mechanism　of　CaF2:10%Eu3+　powder　on　Cr2O7　2-　ion　reveals　that　the　adsorbed　Cr2O7　2-　ions　on　the　CaF2:10%Eu3+　powder　surface　screen　the　latter　from　the　excitation　source,　since　there　is　a　competitive　absorption　of　excitation　light　between　Eu3+　and　adsorbed　Cr2O7　2-.　This　study　expands　the　application　of　old　and　low　cost　CaF2:　Eu3+　powder　into　a　new　area　of　luminescent　probe,　especially　for　Cr2O7　2-　ion　detection.　©　2018　Optical　Society　of　America.