Astragalus extract is the dried root extract of the leguminous plant Astragalus. Dry roots are cylindrical, rarely have differences, the upper end is thick, the lower end is thin, flat at both ends, 20~70cm long, coarse 1~3cm, the surface of the grayish yellow or light brown, all have irregular longitudinal wrinkles or trenches, weak and specific, slightly sweet taste, chewing bean smell. It can enhance immunity, enhance energy, resist fatigue, resist mutation, protect liver and inhibit osteoclast. Astragalus polysaccharide has the effect of lowering blood lipids, that is, lowering cholesterol and triglyceride and increasing high density lipoprotein. It can prevent and treat cardiovascular and cerebrovascular diseases, such as atherosclerosis, coronary artery disease, peripheral vascular disease and hyperlipidemia. Astragaloside IV can significantly reduce blood sugar, glycosylated hemoglobin and urinary protein, and reduce AGEs in renal cortex and serum, indicating that astragaloside IV has antioxidant effects and has inhibitory effect on aldose reductase, as well as inhibiting mesangial cell proliferation and alleviating renal hypertrophy. Adding appropriate excipients in astragaloside IV can be made into oral preparations, which can be used for prevention and treatment of diabetic nephropathy