This article tackles the question of T'ien-tai's theory of three truth and Ts'ao-tung's throry of five positions, that are regarded as the research of the ultimate reality. Ts'ao-tung's throry of five positions presents the dialectical absoluteness of the dynamic ultimate reality. An analysis of the model of the “three-one” in T'ien-tai-buddhism and its development in the Ts'ao-tung's throry of five positions is presented and discussed here.