Abstract: Objective To study the changes on MMP-9 and TMP-1 expression when renal interstitial fibroblast cells (NRK-49F)occurred phenotypic transform induced by transforming growth factor beta-1 (TGF-β₁), and its effects on the secretion of fibronectin(FN). Methods Renal interstitial fi broblast cells (NRK-49F) of rats were stimulated by hTGF-β₁ at different concentrations of 0 ng/ml, 0.5 ng/ml, 1 ng/ml, 2 ng/ml, 5ng/ml, 10 ng/ml. Immune fl uorescence was used to measure the expression of cell phenotype sign α-SMA and Vimentin, and ELISA was used to detect the concentration of FN in supernatant, while Western Blot and Northern Blotting technique was used to measure the expression of MMP-9 and TIMP-1. Results TGF-β₁ at the concentration of 0.5 ng/ml -10 ng/ml induced the expression of α-SMA which represented myo fi broblast appearance, with increasing concentration of TGF-β₁, the expression of α-SMA gradually increased and Vimentin decreased signi fi cantly, furthermore FN secretion were driven up greatly (P< 0.05 or P< 0.01), while TGF-β1 at the concentration of 2 ng/ml markly drove up the expression of TIMP-1 mRNA and protein(P< 0.05 or P< 0.01) , those effects showed concentration-dependent form. However, TGF-β₁ at above concentration had no remarkable effect on MMP-9 mRNA and protein expression (P> 0.05). Conclusion TGF-β₁ can induce renal interstitial fi broblast activation to be myo fi broblast, and promote fi bronectin secretion, whose effects may be related to up-regulation of TIMP-1 expression so as to restrain ECM decompounded.