JiaWeiDangGui (JWDG) decoction has anti-inflammatory and antifibrotic effects, which is used widely for the treatment of various kidney diseases. In previous studies, we have found that JWDG decoction can reduce the quantity of proteinuria, but the mechanism was unknown. Here, we studied the protective effect of JWDG decoction in adriamycin-induced nephropathy on rat. JWDG decoction, at 10 mL/kg/d, 20 mL/kg/d, and 40 mL/kg/d, was orally administered daily for 12 weeks. Therapeutic effects and mechanisms were further examined. The kidney function related biochemical indexes were measured by automatic biochemistry analyzer. The pathomorphological changes were observed using light and transmission electron microcopies. The proteins expressions of podocin, nephrin, collagen IV, and fibronectin (FN) were examined by immunohistochemical staining, and key proteins involved in TGF-β/Smad signaling were evaluated by RT-PCR and western blotting. Compared with vehicle-treated controls, JWDG decoction decreased the quantity of proteinuria; reduced glomerulosclerotic lesions induced by ADR; and preserved the expression of podocin and nephrin. JWDG decoction also inhibited the expression of the collagen IV, FN, and fibrogenic TGF-β. Further studies revealed that inhibition of renal fibrosis was associated with the blockade of TGF-β/Smad signaling and downregulation of snail expression dose dependently. JWDG decoction prevents proteinuria production, podocyte dysfunction, and kidney injury in adriamycin nephropathy by inhibiting TGF-β/Smad signaling.