Objective: To investigate the effect of aliskiren by expression of matrix metalloproteinase- 3 (MMP-3); Tissue Inhibitor of Metalloproteinase-2 (TIMP-2) on kidney of rats with unilateral ureteral obstruction (UUO).In addition, to explore its action in the process of renal interstitial Fibrosis. Materials and Methods: 60 male SD rats were randomly divided into sham operation group, model group and treatment group. Model group and treatment group were ligated and the left ureter transection induced the unilateral ureteral obstruction (UUO) model group began treatment after surgery, Aliskiren administered 50mg / kg oral treatment once a day and sham operation group and model group were given the same amount of physiological saline gavage. After 1 week, 2 weeks; 10 rats of each group were sacrificed respectively, left kidney specimens, do Hematoxylin Oesin (HE) and Masson staining, and by immunohistochemically SABC method to detect renal tissue expression of MMP-3, TIMP-2. Results: HE and Masson staining: the degree of tubular damage in treated rats was less than model group (P <0.05). Immunohistochemistry showed that in the UUO rat model of renal tissue, the expression of the treatment group with a time point of MMP-3 was higher than the model group, and the expression of TIMP-2 is lower than the model group (P <0.05). Conclusion: Aliskiren by regulation of the renal tissue MMP-3 / TIMP-2 ratio imbalance may play a renal protective effect in renal interstitial fibrosis process.