Essential oils were obtained by separate hydrodistillation from arial parts of Centaurea sphaerocephala L. (Compositae). and were analyzed by means of gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS), The main constituent of the essential oil from the aerial parts was caryophyllene oxide (18.3%), followed by benzaldheyde (16.10%), spathulenol (07.5%), humulene oxide II (07.5%), phenylacetaldehyde (05.3%), and α-terpineol (05.2%). As for the study of the methanol extract and the essential oils of this plant, a multitude of test systems were used, namely: DPPH free radical scavenging assay, CUPRAC cupric reducing antioxidant capacity, β-Carotene-linoleic acid test system and ABTS cation radical scavenging assay. The MeOH extract of aerial parts exhibited a strong antioxidant activity evidenced by the β-carotene-linoleic acid test system, the IC50 values were 43.548± 0.357µg/ml. In the case ABTS cation radical scavenging assay, with the IC50 values were 76.434 ± 2.233 µg/ml, while in the DPPH test the IC50 values were 139± 0.622 µg/ml, while in the CUPRAC test the IC50 values were 159.87 ± 2.03µg/ml,. The essential oil extract of aerial parts showed 09.12 ℅ inhibitory activity against butyrylcholinesterase at 200 µg/mL. The highest antibacterial activity was evidenced for the aerial parts MeOH extracts, with inhibition zone medium diameters of 16.33±1.00 mm against Staphyloccocus aureus ATCC25923 at 16 mg/ml and 14±1.00 mm against Escherichia coli ATCC25922 at 16 mg/ml. This analysis constitutes a pioneer study of composition of the essential oil obtained from the arial parts of Centaurea sphaerocephala L. growing in Algeria.