Microbially　induced　carbonate　precipitation　(MICP)is　a　promising　technique　in　geoenvironmental　engineering.　The　metabolic　activity　of　bacteria　is　sensitive　to　external　magnetic　fields,which　will　affect　the　CaCO3　crystal　morphology.　Therefore,nano-Fe3　O4　was　utilized　to　investigate　the　influence　of　magnetic　materials　on　MICP.　Both　MICP　in　solution　environment　and　MICP　on　a　quartz　sand　surface　were　investigated　with　different　nano-Fe3　O4　content.　The　calcium　carbonate　content　(CCC),crystal　types　and　unconfined　compressive　strength　were　analyzed　by　scanning　electron　microscope　(SEM)and　uniaxial　compression　test.　Furthermore,a　series　of　tests　were　conducted　to　reveal　the　mechanism　of　the　effect　of　nano-Fe3　O4　on　MICP.　The　results　showed　that　the　optical　density　at　600　nm　of　bacteria　(OD600)and　bacterial　activity　increased　with　an　increase　in　nano-Fe3　O4　content.　In　the　solution　environment,the　crystal　type　of　CaCO3　was　primarily　vaterite,with　little　calcite,and　it　was　confirmed　by　TG-DTA　testing　that　nano-Fe3　O4　could　facilitate　the　formation　of　vaterite.　Additionally,the　unconfined　compressive　strength　(UCS)and　calcium　carbonate　content　of　MICP-treated　sand　increased　with　an　increase　in　nano-Fe3　O4　content.　Interestingly,CaCO3　presented　in　the　form　of　spheres　in　the　solution　environment,while　it　was　in　the　form　of　rhomboid　imbricate　on　the　surface　of　quartz　sand　particles.　©　2024　Cailiao　Daobaoshe/　Materials　Review.　All　rights　reserved.