Abstract: A preliminary study on chemical composition of root bark from Periploca sepium was accomplished.The result indicated that compound II extracted from the root bark could restrain the growth of wheat and rape seedlings when its concentration was about 3.0~6.0mg/mL;whereas it could promote the seed germination and the growth of wheat and rape when its concentration was lower than 0.75 mg/mL.Another study result showed that compounds III and IV possessed strong contact poisonous effect against Schizaphis graminum,and they also showed stomach toxic and food rejection vitality to Mythimna separate.