In the last decades, the use of essential oils have been increased significantly to affect various aspects of human daily life (cosmetics, pharmacy,pesticide and food industry). The present work aims to study the chemical composition and antioxidant activity of essential oils of Juniperus oxycedrus local (Mostaganem Algeria) extracted by hydrodistillation and steam distillation. The comparative study has permitted to highlight the influence of various parameters on the yield of essential oils (drying, extraction time). Forty components were identified. The characterisation by (GC-MS) showed that the extraction by hydrodistillation gave a better result which was characterised by the presence of α-pinene (37.163 %), sabinene (12.829 %), and limonene (5.795 %) as main chemical constituents. The method of extraction showed that there was a significant influence on the composition of the essential oil. The essential oil of Juniperus oxycedrus showed a strong antioxidant activity. The activity of the oils obtained by hydrodistillation was higher than that obtained by steam entrainment (IC50 = 120 mg ml−1 and IC50 = 160 mg ml−1) with DPPH and β-carotene bleaching tests, respectively. Essential oils of J. oxycedrus could therefore represent good component to be used as an antioxidant agent.