Abstract: The notion of alienation in Karl Marx's Economic and Philosophic Manuscripts of 1844 refers to a contradictory relation and the externalization of transcendental essence.Marx at a mature stage used alienation as a term indicating a contradictory relation.Alienation as a term indicating the externalization of transcendental essence,whose logical function is to break away from the theoretical crisis with the help of Hegelian reversed outlook,is abandoned by Marx at a mature stage.Marx's conversion with regard to the concept of alienation lies in his realization of the full capacity of the term.A young Marx emphasizes the logic of the externalization of transcendental essence,while a mature Marx reexamines alienation from the perspective of the revolution of production mode.The view that in relation to alienation a morality evaluation applies to a young Marx and a history evaluation applies to a mature Marx remains contestable.