Investigation and study is the key for Mao Zedong to realize the sinicization of Marxism, which is specifically manifested in: the activities of investigation and study are the fundamental practice bases for Mao Zedong to realize the sinicization of Marxism; the thought of investigation and study theory constitutes the important theory for Mao Zedong to realize the sinicization of Marxism, and the investigation and study provisions are the importantly institutional arrangements for Mao Zedong to realize the sinicization of Marxism. The fact that Mao Zedong realizes the sinicization of Marxism through investigation and study tells us that we shall continue to promote the sinicization of Marxism in the new historical period, the leading Party cadres shall increase the practice of investigation and study, innovate the theory of investigation and study, and form the system of investigation and study.