To observe the effects of Jianpi Qinghua decoction on P38MAPK in rats with unilateral ureteral obstruction and explore its mechanism.Methods:A total of 90 male SD rats were randomly divided into a sham operation group,a model group,a western medicine group and a traditional Chinese medicine group,and the unilateral ureteral model was made by UUO surgery,and the rats were sacrificed at 7,14 and 21 days after surgery.The serum creatinine and urea nitrogen were detected by biochemical method; the pathological morphology of kidney was observed by HE and Masson staining; the expression of p38,p-p38 and TGF-β1 in renal tissue was measured by WB; the positive area ratio of p38 protein in renal tissue was observed by immunohistochemistry.Results:Compared with the normal group,the content of SCr,BUN,the expression of p38,p-p38,TGF-β1 and the positive area ratio of p38 protein in the model group were all increased(P<0.01,P<0.05); Compared with the model group,the content of SCr,BUN,the protein expression of p38,p-p38,TGF-β1 and the positive area rate of p38 in both the western medicine group and the Jianpi Qinghua decoction group were all decreased(P<0.01,P<0.05).HE and Masson showed that the renal tubules and the renal pelvis in the model group were significantly expanded.Conclusion:Jianpi Qinghua decoction can improve the renal pathological changes in the model rats with unilateral ureteral obstruction,which has a certain protective effect on kidney damage,and the mechanism may be related to down-regulate the protein expression of SCr,BUN,p38,p-p38 and TGF-β1.