Objective: To optimize extraction process of volatile oil from Ferula assafoetida by steam distillation and analyze chemical compositions in volatile oil. Method: With extraction rate of volatile oil as index

conditions for extraction of volatile oil from F. assafoetida were optimized by uniform design.Effect of extraction time on chemical compositions in volatile oil were investigated by GC

conditions were as following:high purity nitrogen as carrier gas

flow rate of carrier gas 1 mL·min-1

injection volume of 0.5 μL

split ratio of 50: 1

total flow of 54.0 mL·min-1

inlet temperature of 250 ℃

detector temperature of 250 ℃.Temperature-rising program was as following:the initial temperature of 60 ℃

kept for 2 min

then temperature rise to 80 ℃ with heating rate of 4 ℃·min-1

kept for 5 min

temperature rise to 180 ℃ with heating rate of 10 ℃·min-1

kept for 5 min

temperature rise to 200 ℃ with heating rate was 4 ℃·min-1

kept 2 min.Extraction process of volatile oil from F. assafoetida was determined by GC and chromatogram similarity. Result: Some compounds in volatile oil were unstable thermally.Optimum extraction process of volatile oil from F. assafoetida was as following:added 6.5 times amount of water and extracted 4 hours.Average extraction rate of volatile oil was 8.32%. Conclusion: This optimized extraction process of volatile oil is reproducible

reasonable and practicable

it can guarantee stability of compositions in volatile oil from F. assafoetida.