Electrochemiluminescence　(ECL)　of　Ru(bpy)(3)(2+)　has　been　widely　used　in　analytical　chemistry.　Herein,　we　present　a　new　approach　to　enhance　the　ECL　of　Ru(bpy)(3)(2+)　by　the　localized　surface　plasmon　resonance　(LSPR)　of　gold　nanorods　(AuNR).　Our　investigations　reveal　that　the　ECL　intensity　could　be　greatly　enhanced　by　controlling　the　distance　between　Ru(bpy)(3)(2+)　and　the　surface　of　AuNRs.　We　call　this　kind　of　surface　plasmon　induced　ECL　enhancement　as　surface-enhanced　electrochemiluminescence　(SEECL).　This　kind　of　SEECL　phenomenon　is　utilized　to　fabricate　a　biosensor　for　ultrasensitive　Hg2+　detection.　The　SEECL　biosensor　is　fabricated　by　self-assembling　AuNRs　and　T-rich　ssDNA　probes　on　gold　electrode　surface.　With　the　presence　of　Hg2+,　the　conformation　of　ssDNA　probes　changed　to　be　hairpin-like　structure　via　formation　of　T-Hg2+-T　structure.　And　Ru(bpy)(3)(2+)　could　insert　into　the　grooves　of　the　hairpin　structured　DNA　probes　to　generate　ECL　emission,　which　could　be　enhanced　by　the　LSPR　of　AuNR.　The　ECL　intensity　of　the　sensor　increased　with　the　concentration　of　Hg2+,　and　a　detection　limit　of　10　fM　Hg2+　in　aqueous　solution　was　achieved.　The　effect　of　different　LSPR　peak　location　of　AuNR　on　the　sensitivity　of　biosensor　has　been　investigated.　The　results　show　that　a　good　overlap　between　the　LSPR　absorption　spectrum　and　the　ECL　emission　spectrum　of　Ru(bpy)(3)(2+)　could　achieve　the　best　ECL　signal　enhancement.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.