The central task of Marx's philosophical revolution is to overcome the limitation of the old philosophy in explaining the world. In the study of philosophy of law and hisdoctoral thesis, Marx ends the old philosophy of “explaining the world” and establishes a new philosophy of “changing the world”. The new philosophy transcends old philosophy in three ways: It removes its concept ontology, and open up the road of philosophy to reality；It overcomes the misunderstanding of idealism and materialism answer to “the riddle of history”；It abandons its transcendental value standpoint and transforms philosophy into the ideological weapon of emancipating the human society.