Abstract:Based on the single factor experiments，the orthogonal test method was employed to optimize the extraction condition of volatile oil from Allium chinense and using gas chromatography-mass spectrometer（GCMS）to analysis the composition.The results of optimum extraction were as following：the ultrasonic time 15 min，ultrasonic temperature 25 ℃，distillation time 2 h，the ratio of material to liquid 1 ∶3（g/mL）and the number of extraction 3 times.Under these conditions，the average extraction yield was 0.035 6%.Moreover，19 kinds of compounds were identified from the Allium chinense volatile oil，in which 8 kinds compounds were sulfur containing compounds.Sulfur-containing coumpounds accounted for 33.83%.It was mainly dimethyl trisulfide（23.12%），sulfide（7.30%）and so on.It laid the foundation for the study of pharmacological activities and product development of subsequent volatile oils.