Abstract: ［Abstract］Objective　To detect the changs in expression of new fibrosis gene SFTPA2 in rat with renal interstitial fibrosis. Methods Sixty-four SD rats，half male and female,were randomly divided into UUO group，sham-operation group，SiRNA group，negative control group，rats were sacrified 3,5,7,14d after operation （n=4 for each day），and the renal tissues of the operated side（obstructed side for model group）were obtained. HE staining was used to evalute the degree of renal tubulointerstitial fibrosis. ELISA was used to detect the expression of SFTPA2，transforming growth factor-β1 （TGF-β1）α-smooth musdeactin（α-SMA），vascular endothelial grouth factor（VEGF）of blood. Western blot was used to detect the expression of SFTPA2，E-cadherin，α-smooth muscle actin（α-SMA）in renal tissues. Results　Histological observations of renal tissue revealed that compared with sham operation group，the degree of renal tubulointerstitial fibrosis gradully increased with time of ureteral obstruction. ELISA showed that compared with sham operation group,the expression of TGF-β1 and SFTPA2 in UUO group increased with time of ureteral obstruction，especially till 7d（P＜0.05），top till 14 d. Compared with negative control group,the expression of TGF-β1 increased till 7d，decreased till 14d（P＜0.05），the expression of SFTPA2 increased till 5d，decreased till 14d（P＜0.05）.Western blot showed that the expression of SFTPA2 increased till 7 d，top till 14d in UUO group；the expression of SFTPA2 increased till 3d，top till 7 d dreased till 14 d，but there was no obvious relationship between them. Conclusion　The progression of increase in expression of SFTPA2 in blood and renal tissues of rats may be related to renal interstitial fibrosis. But there is no obvious relationship between SFTPA2 and TGF-β1.