Si-based　surface　enhanced　Raman　scattering　(SERS)　sensing　technology　is　a　powerful　tool　for　the　detection　of　various　chemical　and　biological　species.　Further　improvement　of　the　simplicity,　stability,　sensitivity,　and　low　cost　of　Si-based　SERS　platforms　is　still　in　great　demand　for　real　applications.　In　this　study,　the　facile　fabrication　of　three-dimensional　(3D)　porous　Si/Au　SERS　platform　with　attractive　SERS　performances　was　reported.　The　developed　method　relied　on　laser-induced　dendrite-like　microstructure　on　the　surface　of　Al-Si　cast　alloy　followed　by　dealloying　Al　from　the　laser　treated　surface,　leaving　a　3D　dendrite-like　porous　Si　substrate.　By　sputtering,　the　substrate　was　coated　with　Au　film　to　form　3D　porous　Si/Au　SERS　platform.　Such　3D　porous　Si/Au　SERS　platform　had　high　SERS　sensitivity　that　enabled　ultralow　concentration　detection　of　R6G　molecules　down　to　10(-15)　M　with　enhancement　factor　in　the　range　of　10(11)　to　10(12).　The　relative　standard　deviation　of　6.2%　was　obtained　from　15　random　SERS　spectrum,　indicating　superior　reproducibility　of　the　as-fabricated　3D　porous　Si/Au　SERS　platform.　(C)　2019　Elsevier　B.V.　All　rights　reserved.