Abstract: The relationship between the Young Marx and Marxism is the core issue of the early Western Marxism. In order to defend for Marx, Althusser answered systematically in theory to this question. He divided Marx's thought into two fundamentally opposite stages in terms of "epistemological break" and "problematic", which is the young Marx as ideology and the mature Marx as science. Humanism, as the problematic of the young Marx, was totally abandoned and then replaced with new problematic by Marx, who therefore produced a scientific theory. Based on the idea that science and ideology were in absolute opposition, he opposed the view that the young Marx belongs to Marxism, and insisted that the essence of Marxism was theoretical anti-humanism. From the angle of defending for Marx, he just extremely defended for the scientific nature of Marxism, although wined in form, ultimately failed in substance.