Abstract: The fresh cinnamon twigs and leaves were pretreated by adding water, adding yeast solution, and aging for 45 days, then steam distillation was used to extract the cinnamon oil. GC-MS was used to identify the chemical composition of the cinnamon oil, and finally UHPLC-QTOFMS technology was used to identify the main chemical components of the methanol extract of cinnamon twigs and leaves, and the differences in the main chemical components of the twigs and leaves of cinnamon were analyzed. The results showed that the extraction rate of cinnamon oil after the yeast liquid pretreated the raw twigs and leaves increased by 20.63% when compared with the control group. Biological pretreatment had no significant effect on the composition of cinnamon oil. Using UHPLC-QTOFMS, 34 kinds of compounds were identified from the methanol extracts of the four groups of cinnamon twigs and leaves, including 17 acids, 5 alcohols, 4 glycosides, 3 aldehydes, 3 flavonoids and 2 esters.Through the difference analysis of 34 compounds, it was found that the relative content of volatile components in the methanol extract of cinnamon twigs and leaves increased after yeast liquid pretreatment, and the relative content of non-volatile components decreased, the change trend was consistent with that under the intervention of natural aging.