Abstract:The extraction process of essential oil from Paeonia rockii was optimized，and the composition and antioxidant activity of the extracted essential oil were analyzed.The essential oil from P.rockii was obtained by subcritical extraction-molecular distillation and steam distillation. The components of the essential oil were analyzed by gas chromatography-mass spectrometry and the antioxidant activity was measured. The results showed that subcritical extraction-molecular distillation had higher yield of essential oil than steam distillation.A total of 79 components were identified from the essential oil obtained by subcritical extraction-molecular distillation，in which geraniol had the highest content（14.664%）. In addition，cedrol，which was rare in Paeonia × suffruticosa essential oil extracted by common methods，was detected in the essential oil. The essential oil of P. rockii obtained by subcritical extraction-molecular distillation showcased scavenging activities against DPPH·，ABTS+·，and·OH and had inhibitory effect on linoleic acid ester peroxidation.In summary，subcritical extraction-molecular distillation can reduce the loss of effective components and obtain high-quality essential oil from P.rockii，which was beneficial for the development and application of value-added products.