Objective:To observe the effect of Cortex Moutan polysaccharide-2b (CMP-2b) on early diabetic nephropathy(DN) in rats.Methods:The rat model of DN was induced by injecting complete freunds adjuvant(CFA) and streptozotocin(STZ) intraperitoneally.The ratio of kidney weight to body weight,the glomerular filtration rate(GFR),the urine microalbumin(MALB),α₁-microglobulin(α₁-MG),urine N-acetyl-beta-D-amidogen glucosamindase(NAG) and the kidney ultrastructure were observed.Results:The results showed CMP-2b could significantly decrease the ratio of kidney weight to body weight and GFR,reduce the level of urine MALB,α₁-MG and NAG,and improve the pathological change of kidney in DN rats.Conclusion:CMP-2b has the therapeutic effects on early DN in rats.