Abstract: Extraction, as well as the antibacterial and antioxidative properties, of the volatile oil from Isodon excia were studied. The volatile oil was extracted by means of the steam distillation (SD)and supercritical CO₂(SFE)method. The processes were optimized by an orthogonal test and the results were compared.An in vitro antibacterial test and a para-DPPH-radical scavenging ability determination were conducted on the oil samples obtained. The results showed that the optimized extraction conditions for the SD method included substrate soaking for 8 h, a substrate:solvent ratio of 1:6, and distillation for 7 h to get an oil yield of 0.186%.Whereas, those for the SFE method consisted of a processing pressure of 30 MPa and extract at 50℃ for 80 min to achieve an oil yield of 0.440%. The antibacterial and antioxidation properties of the volatile oil extracted by SFE were higher than those of the oil extracted by SD method. The bacteriostatic efficacies against various pathogens of the oils were in the order of:Bacillus subtilis >Staphyloccocus aureus >Escherichia coli. The para-DPPH-radical scavenging ability of the oil extracted by SFE was the greatest, followed by that of SD and vitamin C. Both optimized processes were stable, however, the SFE method was considered more suitable for the extraction because its process cycle was shorter, oil yield higher,andantibacterial and antioxidant efficacies of the extracted volatile oil greaterthan the SD method.