The star anise oil was pyrolyzed under helium atmospheres at 300,400,500,600,700,800 ℃,respectively,and the pyrolysates were identified by on-line pyrolysis/gas chromatography-mass spectrometry（Py/GC-MS）.The relative percentage compositions of volatile components were established,and the effects of pyrolyzed temperatures on amounts of volatile components formed during the pyrolyzed procedure were analyzed.Meanwhile,the relationship between the structures of perfume compositions and amounts of flavor compounds was speculated and accounted based on the theory of the structures and property of organic compounds.The results showed that:star anise oil consists of 13 constituents,and trans-anethole aucounts for the highest percentage（94.848%） among all the constituents.28 components were identified in the pyrolysates;star anise oil transferred almost intactly at lower temperature（300-500 ℃）.Some aromatic flavors,xylene and ethylbenzene etc.were produced with the rise of temperature（600-800 ℃）.Trans-anethole is the major flavor component,presenting the highest transfer ratio at 500 ℃.The results could provide a scientific reference for the safe application of star anise oil in tobacco industry.