A　label-free,　ultra-sensitive　and　turn-on　fluorescence　method　to　detect　melamine　has　been　developed.　The　strategy　uses　the　DNA-Ag　nanoclusters　(DNA-AgNCs)　as　the　fluorescence　probe.　The　fluorescence　of　DNA-AgNCs　can　be　quenched　in　presence　of　Hg2+.　However,　When　Hg2+　and　melamine　were　reacted　for　15　min　at　1000　rmp　then　introduced　into　DNA-AgNCs　solution,　a　strong　fluorescence　recovery　could　be　found.　Based　on　this　methodology,　the　changing　fluorescent　intensity　has　a　linear　relationship　with　melamine　in　the　range　of　0.2　mu　M　to　4　mu　M　(R-2=0.997).　The　detection　limit　down　to　0.1　mu　M　was　obtained,　which　is　200　times　lower　than　the　melamine　safety　limit　of　20　mu　M　estimated　by　the　US　Food　and　Drug　Administration.　In　addition,　we　had　been　successfully　applied　this　method　to　detect　melamine　in　milk　powder　and　raw　milk.　(C)　2017　Elsevier　B.V.　All　rights　reserved.