Objective:To investigate the hypoglycemic activity of Sophora japonica L. extract in mice with type 2 diabetes mellitus. MethodsEthanol extract of Sophora japonica L. was acquired by ultrasonic extraction. Mice model of type 2 diabetes mellitus induced by nicotinamide and streptozotocin with intraperitoneal injection and 3T3-L1 preadipocytes differentiation model were established to determine the effects of ethanol extract of Sophora japonica L. on blood glucose and 3T3-L1 preadipocytes differentiation.  Results:After treatment with ethanol extract of Sophora japonica L. by intragastric administration at the daily dose of 100 μg/g for continuous 3 weeks,the level of blood glucose in type 2 diabetic mice was reduced,and the glucose tolerance in oral glucose tolerance test(OGTT)was improved. Differentiation of 3T3-L1 preadipocytes was promoted by ethanol extract at the concentration of 0.4 and 0.8 mg/L.  Conclusion:Ethanol extract of Sophora japonica L. can reduce the blood glucose in type 2 diabetic mice and promote the differentiation of 3T3-L1 preadipocytes. The specific mechanism needs further study.