Abstract: A method of GC-MS for the determination of volatile oil in round cardamom with microwave assisted extraction using non-polar solvent was proposed. The optimized conditions found were as follows: ① absorption medium of microwave: 0.35 g of graphite powder; ② extraction solvent: n-hexane; ③ ratio of mass of sample to volumn of solvent: 2g to 25 mL; ④ extraction time: 30 min. The DB-5 quartz capillary column was used for GC separation and the full-scanning mode was adopted in MS determination. Benzyl alcohol propionate was used as internal standard. The proposed method was applied to the analysis of the sample of round eardamom, 60 compounds were identified and the main components found were eucalyptol (70.34%), β-pinene (6.81%), α-terpineol (3.36%), α-pinene (2.54%) and so on.