Based on the theory of co-evolution between plants and phytophagous insects, the repellent and antifeedant effect of secondary metabolites of non-host plants on diamondback moth(DBM) Plutella xylostella was studied, aimed at finding out the oviposition repellents and antifeedants of insect pests. When the ethanol extracts(Etho Exts) of Bauhinia variegata, Eucalyptus tereticornis, Euphorbia hirta, Duranta repens, Zanthoxylum bungeanum, Magnolia grandiflora, and Nicotiana tabacum were applied respectively, the oviposition repellent rates were all over 80.00%; while after forty-eight hours treatment with the Etho Exts of Euphorbia pulcherrima, Broussonetia papyrifera, Artemisia argyi, Camellia oleifera, Salix babylonica, Euphorbia hirta, Bauhinia variegata, and Setaria viridisa, the antifeedant rates of DBM larvae were all more than 80.00%.