Abstract: Aesthetics and literature were founded on the basis of philosophy.They were closely related to ontology.Materialist dialectics ontology is a basic theory compared to epistemology and they can't be separated or put into opposite positions.The action of replocing ontology with subject will resuct in a serious theoretical confusion.We must distinguish the concept Bf "practice" in materialist dialectics from the "ontology practice" in idealism.Cai Yi's typology had an important inspiring function in developing materialist dialectics ontology.