This study consists to analyze the (Methanol extract (MeOH), Chloroform extract (CH), Ethyl acetate extract (Ac) and Aqueous extract (Aq)) from Silybum marianum seeds. The yields of extracts are ranging from 14.30% to 2.06%. The total polyphenol content of this plant is 24,52±2,78 mg EAG/g and flavonoids are of the order of 15.14 ± 2.28 mg EQ/g. Appalling antibacterial activity, all extracts reacted positively at least one of the bacterial strains tested, Ac and Aq extracts of S. marianum have witnessed a strong antibacterial activity against the most of the strains studied. Evaluation of antioxidant made by following the method of trapping of free radical DPPH and that of β-carotene has shown that MeOH and Ac extracts showed good antioxidant activity greater than 80%. On the other hand, the β-carotene test revealed that the MeOH and Ac extracts have a higher reducing power than the Ch and Aq extracts but relatively lower than that of ascorbic acid (98.04%). The results of separation by high-performance liquid chromatography (HPLC) revealed variability in the phenol and flavonoid content among the plant samples, which may be responsible for biological Silybum marianum activities.