There　is　currently　a　limited　amount　of　research　on　mathematical　models　for　seepage　in　enzyme-induced　calcium　carbonate　precipitation　(EICP)　solidified　sand.　Existing　seepage　models　neglect　the　influence　of　calcium　carbonate　crystals　formed　during　the　EICP　mineralization　process,　thereby　rendering　them　insufficient　in　predicting　the　permeability　behavior　of　EICP-solidified　sand.　To　address　this　issue,　this　study　establishes　a　mathematical　model　for　seepage　in　EICP-solidified　sand　based　on　the　Kozeny-Carman　(K-C)　equation,　incorporating　the　effects　of　calcium　carbonate　crystals　on　pore　filling,　tortuosity,　and　specific　surface　area.　By　comparing　the　theoretical　results　of　the　model　with　experimental　data,　the　feasibility　and　rationality　of　the　model　are　validated.　Furthermore,　the　impact　of　porosity,　mean　particle　size,　calcium　carbonate　content,　and　specific　surface　area　on　the　permeability　coefficient　of　the　samples　is　analyzed.　The　research　findings　indicate　that:　1)　The　proposed　mathematical　seepage　model　can　effectively　represent　the　permeability　coefficient　of　EICP-solidified　sand　under　various　particle　size　distributions　and　cementation　degrees,　demonstrating　broad　applicability.　2)　The　permeability　coefficient　(k)　increases　with　the　rise　in　porosity　(n)　and　mean　particle　size　(D50),　with　k　being　more　sensitive　to　changes　in　porosity　than　mean　particle　size.　3)　The　permeability　coefficient　decreases　significantly　with　increasing　calcium　carbonate　content　and　specific　surface　area.　As　calcium　carbonate　content　increases,　the　sample　porosity　gradually　decreases,　tortuosity　increases,　and　the　water　film　adhering　to　the　calcium　carbonate　crystals　thickens,　leading　to　a　substantial　drop　in　permeability　coefficient.　The　results　of　this　study　provide　a　theoretical　foundation　for　the　engineering　application　of　EICP-solidified　sand.　©　2025　Biodiversity　Research　Center　Academia　Sinica.　All　rights　reserved.