Background　The　pathogenesis　of　hypersplenism　and　the　immune　function　of　the　spleen　in　patients　with　portal　hypertension　(PH)　remain　obscure.　This　study　aimed　to　evaluate　the　morphological　changes　of　blood　spleen　barrier　in　spleen　with　hypersplenism　due　to　PH　and　provide　evidence　for　an　in-depth　investigation　of　the　immune　function　of　the　spleen　with　hypersplenism　and　the　mechanism　of　hypersplenism.　Methods　Spleen　samples　from　12　portal　hypertensive　patients　and　4　patients　with　traumatic　ruptures　of　spleen　were　examined.　The　samples　of　spleen　were　made　into　pathological　sections,　stained　with　Masson　trichrome　stain,　Gomori　stain,　and　CD68,　CD34　immunohistochemistry,　and　were　examined　microscopically　for　the　changes　in　the　distribution　of　collagen　fibers,　reticular　fibers,　macrophages,　and　vascular　endothelial　cells.　The　changes　in　ultrastructure　of　macrophages　and　endothelial　cells　in　marginal　zone　were　also　evaluated　by　transmission　electron　microscopy.　Results　As　compared　to　the　normal　spleen,　the　density　of　macrophage　in　the　PH　spleen　was　decreased,　but　the　macrophages　were　mainly　located　in　the　marginal　zone　and　distributed　around　the　splenic　corpuscle,　with　many　villi　and　pseudopodium-like　protrusion　on　the　cell　surface.　The　accrementition　of　collagen　fibers　was　obvious　around　the　splenic　corpuscle　and　central　artery.　The　increased　reticulate　fibers　encircled　the　splenic　corpuscle　with　more　connection　between　the　fibers.　The　vascular　endothelial　cells　were　in　diffused　distribution,　without　any　regionality　in　PH　spleen,　but　the　vessel　with　enlarged　lumina　increased　in　red　pulp.　Conclusions　The　morphological　changes　of　the　blood　spleen　barrier　can　be　one　of　the　pathological　fundaments　for　the　abnormality　of　the　immune　function　and　the　increased　destruction　of　blood　cells　located　in　the　spleens　of　patients　with　PH.　However,　this　still　entails　clarification.