In our days, the use of medicinal plants in phytotherapy has received a great interest in biomedical research and becomes as important as chemotherapy. This research focuses on the phytochemical study and determination of polyphenolic compounds of various phenolic extracts from the bark of the pomegranate on one hand, and evaluation of antibacterial activity of the other. Phytochemical analysis of the extracts showed the presence of groups of biologically active compounds, including flavonoids, phenols and polyphenols, and tannins with total polyphenol values ranging from 270.5 μg EAG/mg to 284.61 μg EAG/mg, That the flavonoid content varies between 16.83 μg EQ/mg and 38.47 μg EQ/mg. Very interesting bactericidal properties of the phenolic extracts of the pomegranate bark have been found on the bacteria. At the end of the antimicrobial tests, we found that this extract has a very high activity with diameters of the zones of inhibition varying between 12 and 34 mm. MICs of the extract varied between 0.01 and 0.31 mg/ml. This work showed antibacterial activity against five bacteria can contribute to the fight against infectious diseases.