Value nature, value source and value measure are three fundamental questions of the value theory of economics, they label different value theories, by which they also label different economics doctrines. Classical Political Economics had two directions to answer the questions which evolved two opposite value theories and two opposite systems of economic theory. The estrangement and conflict of the two economic systems in the academic field and the social practice forced value theory out of the research scope of economics by different ways. China’s practice of constructing socialist society and market economy raises urgent requirement for integration and breakthrough for the two economic systems, as well as provides realizing condition and, meanwhile, requests deep and extensive research on value theory.