It　is　greatly　significant　to　sense　hexavalent　chromium　(Cr　(VI))　in　water　because　Cr　(VI)　is　one　of　the　most　toxic　heavy　metals　and　is　extremely　harmful　for　human　health　and　environment.　In　this　study,　we　explored　sensitive　surface-enhanced　Raman　scattering　(SERS)　substrates　for　rapid　detection　of　Cr　(VI)　using　magnetic　Fe3O4/ZrO2/Ag　composite　microspheres.　We　firstly　coated　uniform　zirconium　dioxide　layer　around　Fe3O4　cores　to　achieve　Fe3O4/ZrO2　microspheres　and　then　deposited　silver　nanoparticles　onto　their　surface　via　controlled　reduction　of　AgNO3　by　n-butylamine.　The　SERS　sensitivity　of　Fe3O4/ZrO2/Ag　composite　microspheres　were　easily　tailored　via　facilely　changing　the　concentration　of　AgNO3　to　tune　the　coverage　of　silver　nanoparticles　on　the　Fe3O4/ZrO2/Ag.　We　used　4-mercaptobenzoic　acid　(4-MBA)　as　a　Raman　molecule　to　evaluate　the　SERS　activity　of　Fe3O4/ZrO2/Ag.　They　illustrated　excellent　SERS　property　as　well　as　magnetic　responsibility.　The　optimized　Fe3O4/ZrO2/Ag　were　employed　to　quantitatively　detect　Cr　(VI)　in　aqueous　solution.　The　results　showed　good　linear　relationship　between　SERS　intensities　and　logarithm　concentrations　of　Cr　(VI)　(R2　=　0.98)　with　a　detection　limit　of　low　down　to　10−7　M,　which　is　much　lower　than　the　safety　value　(1　μM)　in　drinking　water　of　United　States　Environmental　Protection　Agency.　Moreover,　the　highly　uniform　and　robust　Fe3O4/ZrO2/Ag　composite　microspheres　display　outstanding　signal　reproducibility　(RSD　=　8.34　%)　and　good　storage　stability.　These　results　indicate　that　the　prepared　Fe3O4/ZrO2/Ag　composite　microspheres　have　promising　application　prospect　for　SERS　analysis　of　environmental　pollutants.　©　2020