Abstract: OBJECTIVE To observe the effect of Liuwei Dihuang combined with Huanglian Jiedu Decoction on the expression of serum tumor necrosis factor-α (TNF-α)， interleukin-17 (IL-17)， vascular endothelial growth factor (VEGF) and C reactive protein (CRP) in diabetic nephropathy rats， and to investigate the protective effect on renal function and its mechanism. METHODS 10 SD rats were randomly picked to form normal control group and the left 50 rats were induced into diabetic nephropathy model by intraperitoneal injection of streptozotocin (35 mg/kg) and fed with high calorie forage， then randomly divided into 3 groups: model group， Liuwei Dihuang combined with Huanglian Jiedu Decoction group， and rosiglitazone group. The effects of Liuwei Dihuang combined with Huanglian Jiedu Decoction on serum levels of glucose， insulin， triglyceride， total cholesterol， creatinine， blood urea nitrogen (BUN)， CRP and urinary protein were observed. The expression of the serum TNF-α， IL-17 and VEGF were examined and the kidneys were determined to observe the renal pathological changes. RESULTS Compared with the model group， levels of serum glucose， insulin， triglyceride， total cholesterol， creatinine， BUN， CRP and urinary protein in the Liuwei Dihuang combined with Huanglian Jiedu Decoction group significantly decreased; the serum TNF-α， IL-17 and VEGF levels also decreased， while the kidney organization pathology damage was reduced obviously. CONCLUSION The treatment for diabetic nephropathy rats with Liuwei Dihuang combined with Huanglian Jiedu Decoction could lead to the decrement of urinary protein， improvement of renal function and reduction of renal pathology damage， and the mechanism might related to its action in inhibition extra expression of TNF-α， IL-17， VEGF， CRP in diabetic nephropathy rats.