Abasic　site　(AP　site)　in　the　triplex　structure　can　recognize　specific　target　with　high　selectivity.　In　this　study,　this　character　was　first　applied　to　develop　a　simple,　sensitive,　and　selective　homogeneous　electrochemical　biosensor　for　melamine　determination.　The　assay　combines　the　advantage　of　the　high　selectivity　of　the　DNA　triplex　structure　containing　an　AP　site　to　melamine　and　high　efficiency　of　exonuclease　(Exo)　III-assisted　recycling　amplification.　DNA-1　(T1),　DNA-2　(T2),　poly[dA]　probe　containing　an　AP　site　(8A)　and　methylene　blue-labeled　DNA　probe　(dMB　probe)　were　carefully　designed.　Melamine　can　specifically　locate　in　the　AP　site　through　hydrogen　bonding　interaction　between　thymine　and　melamine　to　make　T1,　T2,　and　8A　close　to　each　other,　therefore,　forming　a　stable　T-melamine-T　DNA　triplex　structure.　Under　the　optimal　conditions,　the　differential　pulse　voltammetric　(DPV)　response　had　a　linear　relationship　with　the　logarithm　of　melamine　concentration　in　the　range　of　1　nM　similar　to　0.5　mu　M.　The　developed　biosensor　has　been　successfully　applied　to　detect　the　migration　of　melamine　from　melamine　bowl.　Result　showed　that　the　migration　in　4%　acetic　acid　solvent　was　the　largest,　which　is　similar　to　that　detected　by　high　performance　liquid　chromatography.　This　homogeneous　electrochemical　sensor　may　have　a　potential　prospect　in　detecting　melamine　in　dairy　products　and　migration　of　melamine　from　multicategory　food　packaging　or　application　materials.