Abstract: The method of steam extracting is used to heat the leaves of cinnamon soaked by water, which can break the cells of cinnamon leaves to release essential oil. Then water is added to the reaction for assistant extracting, followed by centrifuging and cooling down to obtain cinnamon oil. Single factor experiment and orthogonal test show the highest essential oil extraction rate of cinnamon leaves can reach 7.13‰ under the extracting conditions: soaking for 5 hours and 900 W of extracting power, extraction time of 3 hours. Especially, the power has significant influence on cinnamon oil extracting. Finally, the composition of extracted cinnamon oil is analyzed by GC-MS, (Gas Chromatograph-Mass Spectrometer-computer, GC-MS).The result shows that the main compositions of extracted essential oil are trans-Cinnamaldehyde, Diethyl phthalate and Eugenol, while the main components of chemical synthesis products are trans-Cinnamaldehyde and cinnamic acid. The two products can be distinguished quickly through the different components.