In order to further verify whether ursolic acid exerts a protective effect on renal interstitial fibrosis after unilateral ureteral obstruction in rats by activating the Nrf2/HO-1 signaling pathway, in this study, we established group ZnPP + E by the intraperitoneal injection of zinc protoporphyrin (ZnPP, 45 umol/kg, dissolved in DMSO solution 0.5 ml) into the rat's intraperitoneal cavity, which is a specific blocker of the Nrf2/HO-1 signaling pathway. This evidence concerns the gene HMOX1 and Ureteral obstruction.