In　this　study,　enzyme-induced　carbonate　precipitation　(EICP)　combined　with　chitosan　curing　technology　was　used　to　improve　the　mechanical　properties　of　standard　sand,　and　the　curing　effect　of　EICP　combined　with　different　chitosan　contents　was　studied　by　macroscopic　tests,　such　as　the　unconfined　compressive　strength　test,　direct　shear　test,　and　calcium　carbonate　content　test,　and　microscopic　tests,　such　as　scanning　electron　microscope　(SEM)　and　nuclear　magnetic　resonance　(NMR).　The　results　show　that　compared　with　the　pure　EICP　treatment,　the　unconfined　compressive　strength,　shear　strength,　and　calcium　carbonate　content　of　the　sand　treated　by　EICP　combined　with　chitosan　were　significantly　improved,　and　increased　first　and　then　decreased　with　the　increase　of　chitosan　content,　reaching　the　maximum　value　when　the　content　is　1.5%.　The　calcium　carbonate　content　is　positively　correlated　with　the　strength,　indicating　that　calcium　carbonate　crystals　can　effectively　play　a　role　in　filling　and　cementation.　After　the　incorporation　of　chitosan,　the　shape　of　calcium　carbonate　crystals　is　still　mainly　spherical,　but　the　number　and　volume　become　larger.　At　the　same　time,　the　incorporation　of　chitosan　can　greatly　reduce　the　proportion　of　large　pores　and　medium　pores,　significantly　increasing　the　proportion　of　small　pores,　which　greatly　improves　the　pore　structure.　©　2024　American　Society　of　Civil　Engineers.