Abstract: The significant antifeeding action and poisoning of the extracts from Myoporum bontioides against Pieris rapae L. were reported in this paper. The antifeeding rate with 1% methanolic extract andpetroleum ether extract from leaves and stems were above 90% against 3rd instar lareae, and 80% ~86% and 46% ~ 65% against 4th and 5th instar larvae of the insect pest in no-choice tests, respectively. After treatment with methanolic extract and petroleum ether extract in 72h, 86. 1% and 88. 5% ofmertality were obtained, respectively. The LC50 of the extract partitioned with chloroform and methanolfrom methanol extract against 4th instar larvae were 0. 63% and 1. 39%, respectively. In four days aftertreatment, with 1% chloroform extract partitioned from methanol extract, the average weight of 5th instarlarvac was 38. 05% of that in control, and the emergence rate of adult was 4.00% and the rate of growthinhibition was 88. 89%.