Abstract: After many years of laborious management, Li Hongzhang, the founder of the Bei Yang fleet, founded the naval force listing the forth in the world in 1888, which realized the modernization of the Bei Yang defense area. He was not only loyal to the central government, but also loved the country deeply. He was the cabinet minister of a disastrous and oppressed nation. He made great efforts but mined the Bei Yang fleet with his own hand. By objectively analyzing the merits and demerits of his coastal defense idea, we can obtain much enlightenment.