Fennel (seeds of Foeniculum vulgare Mill.) is the widely used aromatic and medicinal plant throughout the world. In this research, supercritical carbon dioxide (SC-CO2) extraction was carried out to extract the aromatic extract from F vulgare seeds under various operating conditions, and aromatic extract samples were characterized for properties such as yield and trans-anethole content. A three-level Box-Behnken design from response surface method was applied to optimize the extraction parameters such as pressure, temperature, and extraction time with an aim to obtain high yield and rich trans-anethole content. The optimum extraction conditions were found to be 177 bar, 40 degrees C and 68 min where the predicted oil yield and trans-anethole contents were found to be 3.798% and 95 mg/g, respectively. Under the optimum conditions, the experimental oil yield was 3.85%, and the content of trans-anethole was 94 mg/g. The results were very close to the values predicted by the model. At the same time, the chemical compositions of the oils from two different extraction methods, hydrodistillation and SC-CO2, were compared. The chemical constituents of oils from two different extraction methods found to be the same, and they showed slight difference in terms of the quantity of the main chemicals. Antibacterial and antioxidant effects of the oils obtained by the two extraction methods were compared, and they showed similar effects.