Artemisia absinthium L. is a spontaneous medicinal plant grown in Algeria. This work aims to enhance the essential oil of Artemisia absinthium (EOAa) from the region of Sidi Bel Abbes by studying the chemical composition of the species and its antibacterial activity. The essential oil is analyzed by gas chromatography coupled with mass spectrometry. We identified 41 constituents, representing 98.43% of the oil total composition; the main compounds of the essential oil were Camphor (25.47%), followed respectively by β-Thujone (18.23%), Camphene (7.21%), and β-Caryophyllene (6.72%). The antibacterial activity of essential oils was evaluated against five microorganisms using the diffusion disc method. The gram-negative micro-organisms (Candida Albicans ATCC 10231, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) had an inhibition zone with an important diameter, between 19 ± 09 mm and 12 ± 06 mm for concentration (100 mg/ml, 50 mg/ml and 25 mg/ml). Furthermore the gram-positive bacteria (Staphylococcus aureus ATCC 25923, Bacillus ATCC 11778) were less sensitive since dilution (25 mg/ml).