The present invention discloses a traditional Chinese medicine preparation for treating diabetic nephropathy, which is prepared from rhubarb polysaccharides, the total flavone of scutellaria root, total alkaloids of rhizoma coptis, and pharmaceutically acceptable auxiliary materials. Pharmacodynamic trials proved that the present invention has the effects of decreasing the blood glucose of the normal mouse, reducing the area under blood glucose concentration curve, and improving the sugar tolerance of the mouse; the present invention can improve the multi-food, the will drink, and the polyuriasymptoms of diabetic nephropathy model rats, reduce urinary protein and urinary albumin, decrease glycosylated hemoglobin, serum cholesterol and serum triglyceride, decrease overhigh creatinine clearance rate, reducing the renal index, alleviate the renal lesion, and have the effect for antagonizing early diabetic nephropathy. In addition, the present invention also discloses a preparation methodof the traditional Chinese medicine preparation and application in preparing a medicament for preventing and controlling diabetic nephropathy.