Objective: To study the anti hyperglycemic effect of rubusoside on diabetic rats induced by streptozotocin (STZ)and its mechanism . Methods: The STZ induced diabetic rats were dived into three groups and were given (ig.) saline, rubusoside and Phenformin respectively once a day. After three weeks, the levels of serum glucose, fructosamine, insulin,SOD were assayed. Results: Rubusoside could reduce the level of serum glucose significantly, enhance the ability of anti oxidation and stimulate the secretion of insulin in STZ induced diabetic rats. Conclusion: The action of rubusoside on secretion of insulin can be explained for the anti hyperglycemic effect.