Objective: To establish the simultaneous determination method for ligustilide

senkyunolide A and n-butylphthalide in the essential oil of Chuanxiong Rhizoma

and to compare the results of HPLC and GC-MS method. Method: The oil was obtained through supercritical CO2 extraction and steam distillation

and the contents of the above three compounds were determined by gas chromatography mass spectrometry (GC-MS) with internal standard method and high performance liquid chromatography (HPLC) with external standard method respectively and methodology was also inspected. Result: The oil yields were 10.49% and 1.54% respectively. The contents of the three compounds were 19.676

15.56

0.957 4 mg per gram crude drug in SFE-CO2 extraction and 2.16

1.56 and 0.11 mg in volatile oil which measured by GC-MS was 1%-4% less than the value which obtained by HPLC. Compared with the result by HPLC

GC-MS is more scientific with 10% higher precision and tenfold detection limit. Conclusion: In the determination of components in the essential oil of Chuanxiong Rhizoma

GC-MS internal standard method is a more accurate and sensitive method whereas HPLC is a relatively convenient and economical method.