Marxism was indeed vulgarized due to scientism in the 20th century, which even limits the development of Chinese social theories nowadays. This paper put forward the idea that it was serious misunderstanding to interpret Marx as prophet or inventor like empiricists who regard finding out eternal laws as the goal of science. In fact, Marx did not propose any so-called “natural laws of historical development”. He articulated that the only thing worth to do was to take note of what happened before his eyes and to become its mouthpiece. Thus, to understand science in the face of social practice, to analyze everything historically and never to thrust “eternal” laws in any era should be taken as the core of Marx’s new science, which is very important to China today.