Abstract: Traditional western political philosophy has deviated from political praxis and lost concerns about human’s living conditions due to its metaphysical fallacy,which is the result that traditional politics could not step out of the methodology of rationality and subjectivity.By deeply reconsidering Aristotle’s concept of praxis with Heidegger’s model,Arendt has put forward a new political methodology of pragmatics,by which she tried to break away from the error of traditional political rationalism and realize the contemporary existentialism turn of political philosophy,and form its critique on Marx’s political ideas.However,methodological pragmatics in Arendt’s politics has been disclosed the characteristics of modern metaphysics,which has fallen into predicament when it criticized Marx’s political philosophy.And most of all,its fallacy of metaphysical methodology cannot eventually escape from the critique and destruction by Marx’s methodology based on real and historical principle.

Key words: Arendt, political existentialism, metaphysics, methodological pragmatics