Au/Fe3O4/GO　nanocomposites　were　successfully　synthesized　by　assembling　Au　nanoparticles　(NPs)　with　Fe3O4/GO　which　were　obtained　by　loading　amino-modified　Fe3O4　NPs　on　graphene　oxides,　and　the　Au/Fe3O4/GO　nanocomposites　were　used　as　a　surface-enhanced　Raman　scattering　(SERS)　substrate　to　enrich　and　detect　polycyclic　aromatic　hydrocarbons　(PAHs).　Firstly,　rhodamine　B　(RhB)　was　used　as　a　probe　molecule　to　investigate　the　effect　of　Au　NPs　size　on　SERS　performance　and　it　was　found　that　Au　NPs　with　an　average　particle　size　of　40　nm　had　the　best　Raman　enhancement　effect.　The　SERS　detection　performance　was　improved　with　the　increase　of　Au　loadings　and　the　optimal　mass　fraction　of　Au　in　GO/Au　composites　was　20%.　Then,　the　effect　of　each　component　of　Au/Fe3O4/GO　nanocomposites　on　SERS　was　explored　by　using　pyrene　as　a　probe　molecule.　The　results　show　that　Au　NPs　played　a　major　role　in　the　enhancement　of　the　Raman　signal　according　to　the　electromagnetic　enhancement　mechanism　and　GO　could　not　only　enrich　the　PAHs　through　π-π　interaction　but　also　generate　strong　chemical　enhancement　to　Raman　signal.　The　existence　of　Fe3O4　was　favor　to　the　quick　separation　of　substrate　from　the　solutions,　which　greatly　simplified　the　detection　procedure　and　facilitated　the　cycle　use　of　the　substrate.　The　detection　limit　of　pyrene　was　10-8　mol•L-1　which　is　significantly　lower　than　that　of　ordinary　Raman,　and　it　is　expected　to　be　used　for　the　enrichment　and　detection　of　trace　PAHs　in　the　environment.　©　2018,　Science　Press.　All　right　reserved.