Abstract: Clove bud oil was pyrolyzed under simulated condition of process of smoking,i.e.,under different temperatures of 300,600 and 900 ℃,and the pyrolytic products obtained at the end of each temperature interval were determined qualitatively or semiquantitatively by Py-GC-MS.It was found that pyrolytic products obtained at 300 ℃ were mainly eugenol,β-caryophyllene and aceto-eugenol,amounting totally to 92.94% (relative content);most of the eugenol were pyrolyzed at 600 ℃ and some hazardous substances were produced at this moment;and all of the eugenol were pyrolyzed with liberation of large amounts of hazardous substances.Based on the main pyrolytic products obtained and on the change of relative contents of the products,a preliminary discussion on the mechanism of pyrolysis of clove bud oil was given,and a theoratical basis was proposed for the evaluation of action of essence in the process of cigarette buring.