Thirty-four bacterial strains were isolated for producing fucoidanase from brown algae, mud and sea water in Nha Trang. Determining six strains that produced intracellular fucoidanase. In which, NITRA-134 strain could synthesize high fucoidanase after 24 hours of cultivation on the medium containing an inductive substance - fucoidan from Sargassum polycystum, meat peptone and at pH 7-7.5. The optimal pH and temperature of the fucoidanase preparation from this strain was found 7-7.5 and 37-40°C, respectively, after precipitating with amonium sulfate.