The article describes the process for finding an optimum solvent for extracting phlorotannin with high antioxidant activities from seaweed Padina boryana in Khanh Hoa waters, hexan, diclometan, butanol, ethylaxetate, axeton, ethanol and methanol were tested as solvents for extracting phlorotannin. Aqueous mixtures of ethanol, methanol and acetone gave the highest value of total phlorotannin contents compared to the orther solvents. In addition, the antioxidant activities of crude phlorotannin extract using different solvent were also evaluated.