Gold　nanoparticles　(AuNPs)　have　a　high　extinction　coefficient　and　a　strong　surface　plasmon　resonance,　the　latter　of　which　is　influenced　by　the　size　of　AuNPs　and　the　surrounding　environment.　In　this　article,　a　DNA　electrochemiluminescence　(ECL)　sensor　was　fabricated　based　on　the　distance-dependence　of　semiconductor　nanocrystals＇　ECL　signal　to　AuNPs.　AuNPs　were　first　deposited　on　the　surface　of　glassy　carbon　electrode　(GCE)　by　cyclic　voltammetry　(CV).　The　mercaptopropionic　acid-capped　CdS　quantum　dots　(QDs)　used　in　this　study　can　covalently　bind　with　amino-terminated　double-stranded　DNA　(dsDNA),　via　the　-CO-NH　bond　to　obtain　a　QDs-dsDNA　compound.　The　QDs-dsDNA　compounds　were　assembled　on　the　surface　of　AuNPs　via　an　Au-S　bond,　using　the　other　distal　of　dsDNA　that　is　labeled　with　thiol,　to　create　the　CdS　QDs-DNA/AuNPs/　GCE　ECL　sensor.　Experimental　conditions,　such　as　the　QDs-dsDNA　density　on　the　surface　of　electrode　and　the　deposition　method　of　AuNPs,　were　then　optimized.　The　surface　properties　of　different　modified　electrodes　were　characterized　by　scanning　electron　microscopy　(SEM),　atomic　force　microscopy　(AFM),　and　electrochemical　impedance　spectroscopy　(EIS).　The　effect　of　AuNPs　on　the　ECL　intensity　of　CdS　QDs　was　investigated　by　controlling　the　DNA　which　lies　between　the　AuNPs　and　the　CdS　QDs.　The　ECL　signal　was　affected　significantly　by　the　length　and　type　of　DNA　strands.　The　sensor　was　used　to　detect　DNA　damage　from　environmental　pollutants　and　exhibited　a　highly　sensitive　response.