Ontology is a theory about existence, which aims to explore the most universal and highest essence of existence. The question of ontology is a question that philosophy as a worldview has to answer, and in order to provide an exhaustive solution to many problems, we cannot leave the study of ontology. An in-depth study of the ontology of Marxist philosophy will also greatly deepen our understanding of Marxist philosophy. In the context of human history, Marxist philosophy considers the practice of material production of human beings based on nature to be ontologically significant. The recognition of the ontological significance of practice, rather than considering it as a category related only to epistemology, is of great significance for the in-depth understanding, study and development of Marxist philosophy.