Abstract: The glandular trichome exudates on leaf surface of burley tobacco topped at different time were analyzed with GC/MS. The results showed that:the major component in the exudate was nicotine, and the composition of exudate of tobacco topped at early-flowering stage was different from that topped at full-blooming stage. Nicotine, solanone and o-xylene were detected in exudates of leaves from all stalk positions, tetratetracontane was detectable in upper leaves, nonacosane in cutter leaves, while triacontane and n-Hexatriacontancd in lower leaves. For early-flowering stage topped tobacco, the nicotine contents in the exudates of upper, cutter and lower leaves were 89.49%, 85.72% and 68.35%, respectively; for full-blooming stage topped tobacco, which were 61.81%, 70.66% and 69.17%, respectively.