Objective To search for starfishes with hopoglycemic activity and orientate the bioactive fractions .Methods Firstly, the crude extracts of four starfishes were subjected to oral glucose tolerance test on normal and diabetic mice .And then the in vitroα-glucosidase activity assay was introduced to confirm the bioactive fractions .Results The crude extract of Asterias rollestoni could lower the blood glucose of normal and diabetic mice after 0.5 h and 1 h.Furthermore, its n-BuOH fraction exhibited potent α-glucosidase inhibitoary activity .Conclusion The n-BuOH extract of Asterias rollestoni had a potent α-glucosidase inhibitoary activity .