The inteference index of population control (IIPC) were used to evaluate the interference effects of alcohol extracts from 20 species of non-preferable plants by means of life table approaches of diamondbach moth(DBM). Among them the alcohol extracts from 8 species of the plants,i.e. Artemisia lactiflora Wall., Amaranthus retroflexus L., Rubia cordifolia L., Chromolaena odorata L., Calystegia hederalea Wall., Stephania longa Lour., Cephalanoplos segetum Bge. and Scirpus wallichii Nees. revealed the better results to control the population of DBM than those from other plants. The IIPCs of all the extracts from plants mentioned above on DBM were all less than 0.2.