Pseudostellaria　heterophylla,　also　called　Tai-zi-shen　(TZS)　in　Traditional　Chinese　Medicine　(TCM),　is　always　used　clinically　to　treat　spleen　deficiency　symptoms.　Polysaccharides　in　TZS　have　various　pharmacological　activities,　including　anti-diabetic,　immune　regulation,　and　myocardial　protection.　However,　the　relationship　between　the　spleen-invigorating　effects　of　TZS　or　its　polysaccharides　and　intestinal　flora　are　not　clear.　This　study　investigated　the　effects　of　TZS　decoction　(PHD)　and　polysaccharide　(PHP)　on　immune　function　and　intestinal　flora　in　a　rat　model　of　spleen　deficiency　syndrome　(SDS)　induced　by　a　decoction　of　raw　rhubarb　(RRD).　PHD　and　PHP　increased　immune　organ　index,　alleviated　inflammatory　cell　filtration,　and　reduced　the　levels　of　pro-inflammatory　cytokines　in　rats　with　spleen　deficiency　syndrome.　In　addition,　the　production　of　butyric　acid　was　promoted　in　PHD　and　PHP　groups.　Moreover,　16S　rRNA　gene　sequencing　showed　that　PHD　and　PHP　reduced　the　relative　abundance　of　Firmicutes　while　increasing　the　one　of　Bacteroidetes;　significantly　increased　the　abundance　of　Lactobacillus　and　decreased　the　abundance　of　Rombutsia;　and　PHP　significantly　increased　the　abundance　of　Alloprevotella.　And　there　was　a　significant　positive　correlation　between　the　alleviation　of　SDS　and　short-chain　fatty　acids　(SCFAs)-producing　bacteria.　These　findings　suggested　PHD　and　PHP,　especially　PHP,　has　a　potential　to　relieve　spleen　deficiency　by　reducing　intestinal　inflammation,　modulating　structure　and　composition　of　gut　microbiota,　and　promoting　the　production　of　butyric　acid.　©　2022,　The　Author(s).