Objective,2,To observe the effect of Shenling Baizhu Powder （SLBZ） on intestinal mucosal barrier in mice with xenograft model of colorectal cancer after chemotherapy.,Methods,2,Thirty-two SPF grade BALB/c mice were subcutaneously inoculated with CT26 colorectal carcinoma cells， and after tumor formation they were randomly divided into four groups （,n,=8 each）： model group， oxaliplatin group， SLBZ group， and SLBZ plus oxaliplatin group. Mice in the model group were given distilled water by gavage （0.2 mL， once daily）， mice in the oxaliplatin group were treated with intraperitoneal injection of 5 mg/kg oxaliplatin （0.2 mL， once every 3 days）， mice in the SLBZ group were treated with 15.6 g/kg SLBZ by gavage （0.2 mL， once daily）， and mice in the SLBZ plus oxaliplatin group were treated with 15.6 g/kg SLBZ by gavage （0.2 mL， once daily） and intraperitoneal injection of 5 mg/kg oxaliplatin （0.2 mL， once every 3 days）. The treatment lasted for 18 days. At the end of treatment，8 mice in each group were selected for serum collection， and the enzyme-linked immunosorbent assay （ELISA） was used to detect serum diamine oxidase （DAO）， D-lactic acid （D-LA）， interleukin-17 （IL-17）， intestinal alkaline phosphatase （IAP） and intestinal mucosal secretory immunoglobulin A （sIgA）. The tumors and spleens of the mice were excised and weighed. Hematoxylin and Eosin （HE） staining and Immunohistochemistry （IHC） staining were used to analyze the effect of SLBZ on intestinal mucosa of mice in histomorphology， and flow cytometry was used to detect the changes of immune microenvironment in tumor tissues.,Results,2,Compared with the tumor growth condition in the model group， the tumor growth was inhibited in SLBZ group and oxaliplatin group， and significantly inhibited in SLBZ plus oxaliplatin group （,P,<,0.05）. Oxaliplatin treatment alone significantly decreased the expression of IAP （,P,<,0.05）， and significantly increased the expression of D-LA （,P,<,0.05） and DAO （,P,<,0.05）. The results of HE staining showed that SLBZ could significantly repair the histological arrangement of colonic villi after chemotherapy and reduce the occurrence of inflammatory reactions. The results of IHC staining showed that SLBZ could significantly increase the expression of colonic tight junction proteins （claudin）， occludin and zonula occludens-1 （ZO-1） in colon of mice after chemotherapy. Compared with the effect of oxaliplatin treatment alone， SLBZ plus oxaliplatin could alleviate the intestinal mucosa barrier damage， and repair the chemotherapy-induced intestinal mucosal barrier damage to a certain extent. Meanwhile， SLBZ could increase the CD8,+, T cell infiltration in the tumor microenvironment.,Conclusion,2,SLBZ can protect the intestinal mucosal barrier after chemotherapy and improve the tumor immune microenvironment， thereby inhibiting the growth of subcutaneously xenograft tumors in mice.