Nowadays, a Numbers of studies have been carried out in the field of ethnopharmacology have shown sufficiently that many plants used in traditional medicine are effective on different pharmacological models. Under traditional conditions, they are less toxic compared to conventional drugs. The influence of the granulometric class the parameters of the chemical composition and on antioxidant activity were investigated. The main purpose of the study is to characterised the powder and evaluated antioxidant activity powder of the plant extracts of Vitex madiensis oliv. according granulometric classes. A crude extract was prepared using hydroalcoholic as the solvent and tested for its antioxidant potential. The best results reveal the interest of the grinding and sieving procedure to enhance the parameters of the chemical composition and antioxidant activity. The 0-180 μm granulometric class led also to the highest content in phenolic compounds (circa 54.7 mg gallic acid equivalent / g of dry matter). These results reveal the interest of the fine grinding and sieving procedure to enhance the parameters of the chemical composition and antioxidant, as significantly higher levels of bioactive compounds were found in ground and sieved fractions in comparison with unground Lippia multiflora Moldenke leaves.