Abstract: Objective To study the protective effect of rosiglitazone on diabetic nephropathy(DN). Methods Immunohistochemical staining and flow cytometry were used to detect the expressions of α-SMA, Vim, TGF-β1 in proximal tubular epithelial cells in type 2 diabetic rats. Results By immunohistochemical staining, the expressions of α-SMA,Vim and TGF-β1 enhanced and depended on time in the rosiglitazone-treated diabetic rats, expressions of those were all between the normal group and diabetic group.And the results were in coincidence with flow cytometry results. Conclusions Rosiglitazone can relieve insulin resistance, correct the disturbance of lipo-metabolism, and delay the interstitial fibrosis.