Tris(2,2　＇-bipyridine)ruthenium(II)　([Ru(bpy)3]2+),　as　a　versatile　molecule,　has　been　widely　applied　in　various　fields,　such　as　photocatalysis,　electrochemiluminescence　and　fluorescence　probes,　solar　cell　and　LED　due　to　its　excellent　optical　and　electrical　properties,　good　water　solubility,　high　chemical　stability.　In　this　work,　we　prepared　electrostatic　nanoaggregates　from　[Ru(bpy)3]2+　and　silver　nanoparticles　(AgNPs@[Ru(bpy)3]2+　ENAs)　as　a　new　type　of　SERS　nanotags.　Each　[Ru(bpy)3]2+　ion　carries　two　positive　charges　with　strong　affinity　to　negative　surfaces,　which　enables　a　strong　electrostatic　interaction　between　[Ru(bpy)3]2+　and　negatively　charged　silver　nanoparticles　(AgNPs)　and　fast　(within　10　min)　formation　of　AgNPs@[Ru(bpy)3]2+　ENAs.　The　prepared　AgNPs@　[Ru(bpy)3]2+　ENAs　had　a　very　strong　and　stable　SERS　activity　due　to　abundant　bipyridine　molecules　in　[Ru　(bpy)3]2+　and　the　location　of　many　[Ru(bpy)3]2+　SERS　reporters　at　the　electromagnetic　＂hot　spots＂　(i.e.　the　junction　of　two　adjacent　AgNPs),　and　thus　could　act　as　novel　and　excellent　SERS　nanotags.　Further　conjugated　with　antibodies,　AgNPs@[Ru(bpy)3]2+　nanotags　were　used　to　develop　new　SERS-based　immunochromatography　test　strips　(SERS-ICTSs),　showing　excellent　sensing　performances.　The　AgNPs@[Ru(bpy)3]2+　ENAs　based　SERSICTSs　not　only　inherit　the　merit　of　fast　and　visualize　quantitative　analysis　from　traditional　ICTSs,　but　also　realize　much　more　sensitive　biosensing　(with　detection　limit　of　25　pg/mL　HCG)　using　the　SERS　technology.