Kidney fibrosis results in chronic renal disease. The current treatment of chronic renal diseases is limited to angiotensin converting enzyme inhibitors and angiotensin receptor blockers. Recently, we found that Wen-pi-tang-Hab-Wu-ling-san (WHW) extract, which has been used to treat renal diseases in herbal medicine for a long time, plays anti-fibrogenic. Here, we investigated the role of WHW in the kidney fibrosis induced by unilateral ureteral obstruction (UUO) in mice. C57BL/6 male mice were subjected to UUO on day 0 and then administered with either WHW (2, 10, or 50 mg/kg of body weight) or vehicle orally from 1 day after UUO to finish the experiment. WHW-administration significantly mitigated the UUO-induced kidney fibrotic changes including tubular atrophy and dilatation, collagen accumulation, expansion of interstitial space and leukocyte infiltration. WHW prevented the increases of oxidative stress by the prevention of UUO-induced decreases of catalase, copper-zinc superoxide dismutase (CuZnSOD) and manganese superoxide dismutase (MnSOD), resulting in reduced production of oxidative stress. Furthermore, WHW reduced transforming growth factor-beta (TGF-beta) expression and phosphorylation of Smad2/3 stimulated by UUO. In conclusion, WHW prevented kidney fibrosis following UUO by the inhibition of inflammation, oxidative stress and TGF-beta/Smad2/3 signaling pathway.