Abstract: In order to explore the defense mode and mechanism of tobacco leaf trichome, Methyl jasmonate (MeJA) was choose to spray on tobacco seedling. After the treatment, trichome morphology, leaf surface chemical composition, gene expression and leaf resistance response to aphid were studied. Scanning electron microscope observation found that the trichome density of the new born leaves increased after MeJA treatment, especially the secreting type which has multicellular head. GC/MS analysis results showed that the content of leaf surface chemical substances increased, which reached the maximum value at the 7th day after treatment. Although the content of cembranoids, which was synthesized and secreted only by trichomes, changed greatly, the expression of its synthesis related genes, CBT and CYP71D16, did not show much difference during the MeJA treatment. It suggests that the complex posttranscriptional regulation mechanism in tobacco glandular hairs existed, which should be explored further.