Abstract: The German Ideology presents that communism is a form of social movement, but the movement must arise under certain conditions. This article intends to explore communism in a sense as a social form, and intends to answer three questions based on the text of The German Ideology. The questions are what is communism, why would it be achieved, and how to realize it. Firstly, communism may have characteristics of idealism, realism, and revolutionism. Secondly, to achieve free and comprehensive development of human, and establish a highly developed material foundation all around the world. Finally, revolution is the means, community is the carrier, and material productivity is the cornerstone to achieve communism.