Bio-cementation　technology　based　on　crude　soybean　urease　is　a　new　environmentally　friendly　foundation　treatment　technology　emerging　in　the　field　of　geotechnical　engineering.　The　uniformity　of　bio-cementation　is　a　pressing　issue　that　needs　to　be　addressed　to　advance　the　application　of　this　technology　in　practical　engineering,　and　soil　particle　size　stands　as　a　significant　influencing　factor.　In　this　study,　13　types　of　sand　with　varying　particle　sizes　were　selected,　along　with　self-extracted　crude　soybean　urease　solution,　to　conduct　urease　percolation　tests,　sand　column　curing　tests,　and　scanning　electron　microscope　(SEM)　examinations.　These　experiments　aimed　to　analyze　the　influence　of　soil　particle　size　on　the　effectiveness　of　bio-cementation　using　crude　soybean　urease　and　explore　its　underlying　mechanisms.　The　findings　reveal　that　soil　particle　size　significantly　affects　the　migration　and　adsorption　of　urease　in　the　crude　soybean　urease　solution.　Smaller　soil　particle　sizes　facilitate　the　adsorption　of　urease.　However,　excessively　small　particle　sizes　(e.g.,　less　than　0.425　mm)　lead　to　the　concentration　of　most　adsorbed　urease　in　the　middle　and　upper　regions　of　the　soil　column.　Conversely,　excessively　large　particle　sizes　(e.g.,　greater　than　4.750　mm)　hinder　urease　adsorption　in　these　regions.　Both　scenarios　tend　to　result　in　uneven　bio-cementation.　Besides　the　amount　of　urease　adsorption,　the　influence　of　soil　particle　size　effect　on　the　biocementation　efficacy　based　on　soybean　urease　is　also　associated　with　factors　such　as　pore　size　within　the　soil　and　the　number　of　particle　contacts　per　unit　volume　of　soil.　Larger　soil　particles　result　in　larger　interstitial　pore　sizes　and　fewer　particle　contacts,　thus　hindering　the　formation　of　effective　calcium　carbonate　crystals.　©　2024　Biodiversity　Research　Center　Academia　Sinica.　All　rights　reserved.