In　this　study,　a　novel　fluorescent　probe　of　acridine-derivitive　N-((N-(2-dimethylamino)ethyl)acridine-4-carboxamide)-alpha-alanine　(N-(ACR-4-CA)(alpha-ALA)　was　synthesized.　The　structure　of　the　new　compound　was　characterized　by　H-1　NMR,　MS,　elemental　analysis,　fluorescent　and　ultraviolet　spectra.　It　was　found　that　DNA　had　the　ability　to　quench　the　fluorescence　of　N-(ACR-4-CA)-alpha-ALA,　and　the　quenched　intensity　of　fluorescence　was　proportional　to　the　concentration　of　DNA.　A　method　for　DNA　determination　based　on　the　quenching　fluorescence　(lambda(ex)　=　260　nm,　lambda(cm)　=　451　nm)　of　N-(ACR-4-CA)-alpha-ALA　was　established.　Under　optimal　conditions,　the　linear　range　is　0.05-2.0　mu　g　mL(-1)　for　both　fish　semen　(fsDNA)　and　calf　thymus　DNA　(ctDNA).　The　corresponding　determination　limits　are　9.1　ng　mL(-1)　for　fsDNA　and　8.7　ng　mL(-1)　for　ctDNA,　respectively.　The　results　suggested　that　the　interaction　mode　between　N-(ACR-4-CA)-alpha-ALA　and　DNA　was　intercalative　binding.　The　intrinsic　binding　constant　was　determined　and　the　result　showed　a　large　binding　constant　of　N-(ACR-4-CA)-alpha-ALA　with　DNA.　(c)　2008　Elsevier　B.V.　All　rights　reserved.