Abstract: The volatile oils from Michelia maudiae Dunn and Michelia chapensis Dandy leaves were extracted by supercritical carbon dioxide. Their compositions were detected by GC-MS, meanwhile antioxidation activities such as scavenging rate on DPPH free radical and reducing power were determined. Results show that the constitutes of M. maudiae were terpene 35.35%, ester 15.12% and alcohol 9.09%. The rest 37.02% were terpene oxydirivatives. the constitutes of M. chapensis were terpene 28.49%, ester 11.12% and alcohol 1.94% . The rest 54.55% are terpene oxydirivatives. When the concentrations of the two volatile oils were 50 mg/L, the scavenging rate on DPPH free radical attained to saturation.The concentration of volatile oil is higher, the reducing capability is stronger. Compared with common antioxidations, the antioxidant capacity of two species Michelia were stronger than that of PA,PG and Vc.