Objective To investigate the effect of celecoxib on diabetic rat kidney tissue collagen, transforming growth factor β1 (TGFβ1) and Smad7. Methods 30 Wistar rats were randomly divided into normal control group (A, n=10), diabetic group (B group, n=10) and celecoxib treatment group (C group, n=10). The diabetic rat models were established in B and C groups by injection of STZ. The Models were established after 3 d treatment group received celecoxib (8mg/kg • d) for gavage, B and C groups with an equal volume of saline. After 3 months, the rats were sacrificed and kidney tissues underwent routine paraffin wax Masson staining tissue sections, the surface density of collagen fibers level was counted. The expression of TGFβ1 and Smad7 mRNA were dectected by RT-PCR.  Results Compared with the normal control group, the collagen fibers of kidney tissue in diabetic rats, TGFβ1 Smad7 mRNA expression was significantly increased (P <0.05), Smad7 mRNA expression was significantly decreased (P<0.05). The collagen fibers in Celecoxib treated rats, TGFβ1 mRNA expression was significantly lower than the diabetic group and higher than the normal control group (P<0.05), Smad7 mRNA expression was increased than the diabetic group and decreased than the normal control group (P <0.05). Conclusion Celecoxib can alleviate development of renal fibrosis in rats．The possible mechanism might attribute to the regulation of collagen fiber, transforming growth factor-βl and Smad7.