Here,　we　report　a　novel,　highly　sensitive,　selective　and　economical　molecular　beacon　using　graphene　oxide　as　the　＂nanoquencher＂.　This　novel　molecular　beacon　system　contains　a　hairpin-structured　fluorophore-labeled　oligonucleotide　and　a　graphene　oxide　sheet.　The　strong　interaction　between　hairpin-structured　oligonucleotide　and　graphene　oxide　keep　them　in　close　proximity,　facilitating　the　fluorescence　quenching　of　the　fluorophore　by　graphene　oxide.　In　the　presence　of　a　complementary　target　DNA,　the　binding　between　hairpin-structured　oligonucleotide　and　target　DNA　will　disturb　the　interaction　between　hairpin-struclured　oligonucleotide　and　graphene　oxide,　and　release　the　oligonucleotide　from　graphene　oxide,　resulting　in　restoration　of　fluorophore　fluorescence.　In　the　present　study,　we　show　that　this　novel　graphene　oxide　quenched　molecular　beacon　can　be　used　to　detect　target　DNA　with　higher　sensitivity　and　single-base　mismatch　selectivity　compared　to　the　conventional　molecular　beacon.