Surface-enhanced　Raman　scattering　(SERS)　is　a　molecule-specific　ultra-sensitive　spectroscopic　technique.　With　the　development　of　portable　Raman　equipment,　it　has　become　possible　to　apply　the　SERS　technique　for　rapid　on-site　detection.　Therefore,　the　search　for　materials　with　excellent　surface　plasmon　resonance　(SPR)　activity　and　high　stability　has　become　an　important　research　focus　in　recent　years.　In　this　study,　we　successfully　prepared　plasmonic　nanostructures　with　a　large　number　of　SERS　＂hotspots＂　using　alloy　nanoparticles　(NPs)　with　tunable　gold-silver　mole　ratios.　These　structures　were　composed　of　numerous　narrow　gapped　gold-silver　alloy　NPs　with　diameters　ranging　from　10　to　100　nm.　SERS　property　evaluation　showed　that　the　prepared　alloy　SERS　substrates　had　good　uniformity,　and　the　performance　of　the　substrates　rapidly　improved　as　the　Ag　content　increased.　Gold-stabilized　Au-Ag　alloy　SERS　substrates　combine　the　high　performance　of　the　Ag　SERS　substrate　and　the　excellent　stability　of　Au.　In　addition,　the　wavelength　of　the　SPR　can　be　tuned　by　adjusting　the　mole　ratio　of　Au　and　Ag　to　satisfy　different　excitation　wavelengths.　Thus,　the　Au-Ag　alloy　SERS　substrates　we　prepared　show　good　comprehensive　performance.　The　lowest　concentration　of　rhodamine　6G　that　can　be　homogeneously　detected　by　the　prepared　Au(1)Ag(8)alloy　substrate　is　5　x　10(-12)　M,　and　the　enhancement　factor　is　5.1　x　10(8).　Finite-difference　time-domain　(FDTD)　theoretical　calculations　further　confirmed　our　experimental　results　and　theoretically　demonstrated　the　unique　properties　of　the　Au-Ag　alloy　SERS　substrates.