To investigate the effect of Guilong decoction on the immune mechanism of rats with diabetic angiopathy.Methods:Eighty rats were randomly divided into blank control group,model control group,cilostazol group,Guilong (low,middle,high dose) group.Models of rats with diabetic angiopathy were made.Rats in the blank control group and the model control group were daily fed with distilled water.The cilostazol group daily fed rats with 1.67 mg/kg cilostazol; Guilong decoction group gave different doses of Guilong decoction.After 56 days,the experimental rats were killed,and the blood glucose and immune indices in serum of rats were detected.The atherosclerotic aortic lesions were observed under the microscope.Results:IgM,IgA and C3 immune indexes of diabetic angiopathy in rats were increased,IgG was decreased.The high,middle and low dose Guilong decoction could return the immune index in rats with diabetic angiopathy to normal.Conclusion:Guilong decoction can effectively regulate the immune imbalance of rats with diabetic angiopathy.